NEET Biology MCQs The Transport In Plants

NEET Biology MCQs The Transport in Plants

The given diagram shows cotransport method of two molecule. Labelled it correctly and choose the
correct option accordingly a) A-Uniport, B-Symport, C-Antiport
b) A-Uniport, B-Antiport, C-Symport
c) A-Symport, B-Uniport, C-Antiport
d) A-Antiport, B-Uniport, C-Uniport
What are the aquaporins in facilitated diffusion process?
a) Membrane proteins b) Carrier proteins c) Channel proteins d) Carrier lipids
Which of the following osmotic situations does the figure demonstrate? a) Plasmolysis
b) Turgid
c) Reverse plasmolysis
d) Diffused
Read the following statement and choose the correct one from the codes given below
I. The apoplastic movement of water takes place exclusively through intercellular spaces and cell wall
without crossing any membrane
II. Symplastic movement occurs from cell to cell through plasmodesmata, 𝑖.𝑒., adjacent cells are connected
through plasmodesmata
III. Permeability of a membrane depends on its composition and chemical nature of the solute
IV. Solutes present in a cell increases the free energy of the water or water potential
a) I, II and III b) I, II and IV c) II and IV d) I and IV
When sugars enter sieve tubes, water flows by osmosis, resulting in
a) Water potential b) Osmotic gradient c) Turgor pressure d) DPD
The evaporative loss of water from the exposed part of plant is called
a) Transpiration b) Guttation c) Loss of water d) Water bleeding

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Which one of the following is not related to guttation?
a) Water is given out in the form of droplets b) Water given out is impure
c) Water is given out during daytime d) Guttation is of universal occurance
Whose water potential is less than water potential of root hair during the water absorption by
root hair?
a) Gravitational water b) Soil solution c) Pure water d) Vacuolar sap
A thin film of water is held by the soil particles under the influence of internal attractive force. It
is called
a) Hygroscopic water b) Gravitational water
c) Combined water d) Capillary water
Study the following statement and choose the correct option(s) from the codes from below
I. Root pressure provides a light push in the overall process of water transport
II. Root pressure causes the flow of water faster through xylem than it can be lost by transportation
III. In symplast pathway, water move exclusively through the cell wall and intercellular spaces
IV. Guttation is a cause of transpiration pull
V. Most plants fulfill their water requirement by transpiration pull
a) I, II and III are correct while IV and V are incorrect
b) IV and V are correct while I, II and III are incorrect
c) I and V are correct
d) II and III are correct while I, IV and IV are incorrect
What is required for the transport of substances through a membrane from a region of lower
concentration to higher concentration?
a) Input of energy b) Output of energy c) Facilitated diffusion d) Nothing is required
Which of the following statement is correct?
a) DPD=OP-WP b) DPD=OP+WP c) DPD=WP-OP d) DPD=TP+OP
Choose the correct combination of labeling of stomatal apparatus of dicot and monocot leaves a) A-Epidermal cells B-Subsidiary cells C-Chloroplast D-Guard cells E-Stomatal aperature
b) A-Epidermal cells B-Guard cells C-Chloroplast D-Subsidiary cells E-Ctomatal aperature
c) A-Epidermal cells B-Subsidiary cells C-Chloroplast D- Stomatal aperature E- Guard cells
d) A- Subsidiary cells B- Epidermal cells C-Chloroplast D- Stomatal aperature E- Guard cells
In a plant organ, which is covered by periderm and in which the stomata are absent, some
gaseous exchange still takes place through
a) Aerenchyma b) Trichomes c) Pnenumatophores d) Lenticels
Identify the correct statements from the following:
I.Accumulation of K+ ions in the guard cells does not require energy.
II.A high pH favours stomatal opening.
III.Movement of chloride ions into the guard cells accrues in the response to the electrical
differential created by K+ ions.
IV.With the entry of several K+ ions and chloride ions, the water potential of guard cells increases.
a) I and III b) I and II c) II and III d) III and IV

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Which one of the following is the reason for higher rate of transpiration in Sorghum as compared
to maize?
a) Increased shoot/root ratio b) Increased rate of respiratory quotient
c) Increased rate of phototsynthesis d) Decreased shoot/root ratio
If turgidity of a cell surrounded by water increases, the wall pressure will
a) Increase b) Decrease c) Fluctuate d) Remain unchanged
In plants; which of the following are/is translocated through phloem?
a) Hormones b) Amino acids c) Sugars d) All of these
Root pressure is due to
a) Diffusion b) Passive transport c) Active transport d) Osmosis
What is depicted by the given diagram below? a) Measuring the rate of transpiration b) Demonstration of ascent of sap
c) Demonstration of transpiration d) Both (a) and (c)
Choose correct statements regarding the flow of sap in xylem?
I. Flow is driven by higher concentration of sugar in the vessel elements
II. Flow from root to twigs and leaves would be reduced if leaves are removed
III. In the morning, sap begins to flow first in the twig then in trunk
IV. Rapid flow of water put tissues under pressure much more than atmospheric pressure
a) I and IV b) II and III c) I, II, III and IV d) No one is correct
Stomatal opening is regulated by
a) Light b) Temperature
c) Atmospheric humidity d) Wind
The direction of movement in phloem is …A… and that of xylem is …B… .
Choose the correct pair of options
a) A-downwards; B-downwards b) A-only upwards; B-only downward
c) A-unidirectional; B-bidirectional d) A-bidirectional; B-unidirectional
Which of the following theories for ascent of sap was proposed by an eminent Indian scientist J C
Bose?
a) Pulsation theory b) Relay pump theory
c) Transpiration pull theory d) Root pressure theory
The potential energy of water is referred as
a) Water potential b) Osmotic potential c) Gravity potential d) Pressure potential
If two solutions have the same osmoregularity, they are said to be
a) Hypertonic b) Hypotonic c) Isotonic d) None of these
Plant obtain carbon and most of their oxygen from
a) Soil b) Water
c) CO2 from the atmosphere d) Symbiotic organisation
When plant cell is kept in saline drip, cell
a) Decrease in size b) Bursts out c) Increase in size d) Unchanged

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Carrier protein, which allows the diffusion of two type of molecules in the same direction is
a) Symport b) Antiport c) Both (a) and (b) d) Uniport
Hydroponics is the method of
a) Water conservation b) Plant development in water without soil
c) Plant development without soil d) Plant development in saline soil
Imbibition is always accompanied by swelling or increase in the volume of imbibint However, the increase
in the volume of the imbibant is
a) More than the volume of water imbibed
b) Same as the volume of the water imbibed
c) Less than the volume of the water imbibed
d) Depends upon the type of imbibant
Which of the following is responsible for the transport of water and minerals from roots to stems, leaves,
flowers and fruits in rooted plants?
a) Xylem b) Phloem c) Either (a) or (b) d) Both (a) and (b)
Loss of liquid water by guttation occurs through
a) Hydathodes b) Stomata c) Cuticle d) Bark
The process by which water is absorbed by solids like colloid causing them to increase in volume,
is called
a) Osmosis b) Plasmolysis c) Imbibition d) Diffusion
Choose the correct combination of labeling of the potato osmoscope experiement. a) A-Final level B-Dotpin
C-Initial level D-Sugar solution
E-Potato tuber
b) A-Initial level B-Dotpin
C-Final level D-Water
E-Potato tuber
c) A-Final level B-Dotpin
C-Initial level D-Water
E-Potato tuber
d) A-Final level B-Dotpin
C-Initial level D-Water
E-Container
How will you distinguish between the method of transport between xylem and phloem?
a) Active transport move xylem but not phloem sap
b) Transport, in xylem is unidirectional and saps move upward, while phloem sap moves ups and down
c) Transpiration does not move xylem sap, but it moves phloem saps
d) Transport of substances take place from source to sink by both the tissues
Which one of the following is not an antitranspirant?
a) PMA b) BAP c) Silicon oil d) Low viscosity
Statoliths are involved in

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a) Phototropism b) Hydrotropism c) Chemotropism d) Gravitropism

In plasmolysed cell, the space between nucleus and plasma membrane is occupied by
a) Hypotonic solution b) Hypertonic solution
c) Isotonic solution d) Air
The sugarcane plant has
a) Dumb bell-shaped guard cells b) Pentamerous flowers
c) Reticulate venation d) Capsular fruits
Water potential and osmotic potential of pure water is
a) Zero and zero b) 100 and zero c) 100 and 100 d) Zero and 100
When pea seeds and wheat seeds are put in water, which of the two will imbibe more water?
a) Wheat seeds b) Pea seeds
c) Both will imbibe equal amount of water d) Pea seeds imbibe water only at alkaline pH
Nyctinasty and seismonasty in plants like bean and touch me not are produced due to
a) Reversible osmotic potential in the cells
b) Reversible turgor pressure in the cell of their pulvini
c) Due to less pressure potential in the cells
d) Presence of less turgidity in the cells
Following statements are related with the diffusion of coloured molecules across a membrane. Select the
correct statement, which shows the fastest rate of diffusion?
a) An internal concentration of 15% and external
concentration of 10%
b) An internal concentration of 25% and external
concentration of 50%
c) An internal concentration of 50% and external
concentration of 25%
d) Both (b) and (c) shows fastest rate of diffusion
Choose the false statement
a) If bark of tree is girdled from main stem, the plant dies because ascent of sap is stopped
b) If xylem is girdled from main stem, wilting of leaves tales place
c) In the flowerering plant food is transported in the form of dissacharide sucrose
d) In Girdling experiment, in a plant, root dies first
Sunken stomata is found in the leaves of
a) Trifolium b) Lemma c) Nerium d) Lilium
Who proposed cohesion theory of water movement in plants?
a) JC Bose b) Priestly c) Dixon and Jolly d) TV Englemann
Study the following picture and the statements given below and choose the correct option

I. The above diagram shows the net movement of water from the dilute to concentrated solution
II. The two solutions are separated by a differentially permeable membrane
III. Water molecule strikes the membrane randomly on both the sides and pass through the same
IV. Diffusion of water does not occur from its lower chemical potential to higher chemical potential
a) I, II, III and IV b) I, II and III c) I, II and IV d) I and IV

Read the following statements and choose the correct option given below
I. Major account of transpiration takes places through surface/margin of leaves
II. A little amount of water is lost through stem, this is reffered to cauline transpiration
III. Transpiration is comparatively a slow process then evaporation

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IV. Transpiration driven ascent of sap does not depend on cohesion, adhesion and surface tension
properties of water
a) I, II, III and IV b) I, III and II c) I, II and IV d) II, III and IV

Direction of translocation of organic food or solutes, is
a) Upward b) Downward c) Radial d) All of these
The water available to plants for absorption is
a) Gravitational water b) Hygroscopic water
c) Capillary water d) Chemically bound water
Which of the following theory gives the latest explanation for the closure of stomata?
a) ABA theory b) Munch theory
c) Starch glucose theory d) Active K+transport theory
What will be the effect of accumulation of K+ions in guard cells?
a) Water potential increases b) Water potential decreases
c) Loss of turgidity d) Exosmosis
Why all the minerals present in soil can not be passively absorbed by roots?
a) Mineral existence as ions is more than absorption
b) Due to less concentration of ion in root interior than soil
c) Due to more concentration of ions in root interior than in soil
d) None of the above
Which one is not the job of zone of cell differentiation in roots?
a) Mineral uptake b) Water uptake c) CO2 uptake d) O2 uptake
Which one is against the theory of ascent of sap given by Dixon and Jolly?
a) Pores in treachery elements b) Cohesion force of water molecules
c) Adhesion force of water molecules d) Requirement of ATP
Attraction of water molecules to polar surfaces is known as
a) Cohension b) Capillarity c) Surface tension d) Adhesion
The epidermal trichomes help in
a) Transpiration and exchange of gases b) Protection from desiccation
c) Protection and reduction of transpiration d) Exudes water drops from their tips
In land plants, the guard cells differ from other epidermal cells in having
a) Mitochondria b) Endoplasmic reticulum
c) Chloroplasts d) Cytoskeleton
The values of osmotic potential (π) and pressure potential (ρ) of cells A, B, C and D are given
below.
Cell 𝛑 𝛒
A -1.0 0.5
B -0.6 0.3
C -1.2 0.6
D -0.8 0.4
Identify the correct sequence that shows the path of movement of water from among the
following.
a) D→C→A→B b) B→D→A→C c) B→C→D→A d) C→B→A→D
The experimental set up shown in the adjacent diagram is for

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a) The demonstration of development of suction force due to transpiration
b) Measuring the rate of transpiration
c) The demonstration of ascent of sap
d) The demonstration of anaerobic respiration

Arrange the events of opening stomata in correct sequence and choose the correct option accordingly
I. Lowering of osmotic potential of guard cells
II. Decline in guard cell solute
III. Rise of potassium ion level in guard cells
IV. Guard cells absorb water from neighbouring epidermal cells
V. Guard cells become flaccid
VI. Guard cells swells and make a pore between them
a) III, I, IV, V b) I, II, III, IV, V, VI c) III, I, IV, VI d) III, I, IV, VI, II, V
In the given flow chart, the pathway of water movement is shown from soil to xylem. Identify A-E and
choose the correct option accordingly a) A-Stomatal pore, B-Endodermis, C-Casperian strip,
D-Symplast, E-Apoplast
b) A-Plasmodesmata, B-Palisade, C-Medullary rays,
D-Symplast, E-Apoplast
c) A-Plasmodesmata, B-Endodermis, C-Casperian
strip, D-Apoplast, E-Symplast
d) A-Stomatal pore, B-Guard cell, C-Medullary rays,
D-Apoplast, E-Symplast
Water potential increases due to
a) Addition of solute b) Evaporation
c) Addition of inorganic substances d) Increase in pressure
Why seeds imbibe and swell after keeping in water?
a) OP inside the seed is low
b) OP of water is high
c) Water potential gradient developes between the seed coat and water
d) Diffusion pressure deficit of seed is very high
If you are given a task to analyse phloem sap chemical, which of the following will be present in least
concentration?
a) Water b) Sugar
c) Minerals and nitrogen d) Hormones

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Some elements like calcium are not remobilised because they are
a) Structural component b) Heavy metals c) Less charged d) Macromolecules
Movement of molecules in three forms of matter, from a region higher concentration to a region of lower
concentration can be termed as
a) Osmosis b) Passive transport c) Diffusion d) Active transport
In plants, water supply is due to
a) Osmosis b) Imbibitions c) Guttation d) Adhesion force
Which part of root absorbs both water and minerals?
a) Zone of cell differentiation b) Zone of cell formation
c) Zone of cell elongation d) Terminal portion of root
Diffusion pressure deficit is also called
a) Suction pressure b) Turgor pressure c) Osmotic pressure d) None of these
Which of the following transport induces conformational changes in proteins?
a) Simple diffusion b) Osmosis c) Facilitated diffusion d) Plasmolysis
Diffusion, a process occur(s) along the concentration gradient is actively involved in
a) Transpiration b) Respiration c) Photosynthesis d) All of these
Which of the following mechanism can explain the transport of sucrose from source to sink?
a) Osmotic movement of water into sugar loaded sieve tube cells which create a higher hydrostatic
pressure into the source than in the sink
b) Tension created by differences in pressure potential between source and sink
c) Active absorption of sucrose through sieve tube membrane driven by a specific pump
d) Transpiration and active transport of sugar from source to sink
Which of the following cells are not related to the structure of stomata?
a) Sclerenchymatous cells b) Epidermal cells
c) Guard cells d) Accessory cells
Choose the correct option to label 𝐴-𝐶 in the given diagram of stomatal apparatus A B C a) Stomatal aperture Subsidiary Guard cells
b) Cellulose micro fibrils Subsidiary cells Stomatal aperture
c) Stomatal aperture Guard cell Epidermal cells
d) Stomatal aperture Guard cell Cellulosic micro fibrils
Water lost in Guttation is
a) Pure water b) Impure water c) In vapour form d) Either (A) or (B)
The approximate length of root hair zone in plants
a) 1-10 cm b) 1-15 cm c) 1-6 cm d) 1-20 cm
When the conditions are dry, a grass leaf curls inward to minimize water loss due to the pressure
of
a) Thick cuticle b) Large xylem cavities
c) Parallel venation d) Bulliform cells
Cell A has Ψw−3 bars and cell B has Ψw−8 bars. The movement of water will be from
a) Cell A to cell B

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b) Cell B to cell A
c) Data insufficient
d) Water can not move in negative value of ΨW

Transpiration is measured by
a) Photometer b) Porometer c) Auxanmeter d) Respirometer
A cell swells up when kept in
a) Hypotonic solution b) Hypertonic solution
c) Isotonic solution d) All of the above
Which of the following statements are true/false?
I. The positive hydrostatic pressure is called turgor pressure.
II. Wall pressure exerts to prevent the increase of protoplasm size.
III. Diffusion is more rapid in liquids than in gases.
IV. Diffusion of water through a semi-permeable membrane is called imbibition.
V. Osmosis is movement of substance, which takes place along a diffusion gradient.
a) I and II are true, while III, IV and V are false
b) I and III are true, while II, IV and V are false
c) I and IV are true, while II, III and V are false
d) I and IV are true, while II, III and IV are false
When a plasmolyzed cell is placed in a hypotonic solution then water will move inside the cell.
Which force causes this?
a) DPD b) OP c) WP d) None of these
Which one of the following denotes the water potential of the mesophyll cell in wilted condition?
a) Equal to the value of osmotic potential
b) Equal to the value of pressure potential
c) Greater than the value of its osmotic potential
d) Equal to zero
Sugar stored in roots may be mobilised to become a source of food in the
a) Winters b) Early spring c) Summers d) Early summers
Choose true and false statements from the following
I. Mycorrhizal association between fungus and root of plant (𝑃𝑖𝑛𝑢𝑠) is often obligate
II. 𝑃𝑖𝑛𝑢𝑠 and orchid seeds can germinate and grow into plant in absence of mycorrhizal association
III. Absorption of water along with mineral solute by root hairs is purely a process of diffusion
IV. In apoplast pathway, movement of water takes place through cell wall and intercellular spaces
V. Fungal hyphae provide sugar and organic internal to root
Choose the correct option
a) I, II and III are true while IV and V are false
b) IV, and V are true while I, II and III are false
c) I and IV are true
d) I, II and V are true
Which of the following is the unit of measurement of water potential?
a) Watt b) Joule c) Pascal d) Litre
Which type of water is used by the plants?
a) Gravitational water b) Capillary water c) Hygroscopic water d) Bound water
Water in the vessel of xylem in tall plant is
a) Pushed
b) Pulled
c) Pulled and pushed

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d) First pushed and it is pulled slowly

Sunken stomata are usually found in the leaves of
a) Xerophytes b) Hydrophytes c) Mesophytes d) Sciophytes
A leaf peeling of Tradescantia is kept in a medium having 10% NaCl. After a few minutes, if we
observe the leaf peel under the microscope, we are likely to see
a) Entry of water into the cell b) The cells bursting out
c) Diffusion of NaCl into the cell d) Exit of water from the cell
Identify the process taking place in the given experimental setup and choose the correct option a) Osmosis b) Plasmolysis c) Imbibition d) Diffusion
Stomata which can open at night, are present in
a) Xerophytes b) Gametophytes c) Hydrophytes d) None of these
This hormone affects opening and closing of stomata.
a) Zeatin b) Abscisic acid c) Ethylene d) GA
Transport of gases, hormones, photosynthetase and organic solutes in plants is
a) Multidirectional
b) Unidirectional
c) In two direction
d) First unidirectional then divides to many direction
Fensom and Jones suggested, which of the following method for translocation of solute?
a) Osmosis b) Plasmolysis c) Diffusion d) Electro-osmosis
Which statement can be shared by facilitated diffusion and active transport?
a) Both need carrier transporter, which are sensitive
to inhibitors that reacts with protein side chains
b) Energy is required by both the processes
c) No energy expenditure in these processes d) Both use carbohydrates to move molecules across
the membrane
Which of the following has maximum water potential?
a) Pure water b) 2% sucrose solution
c) 4% glucose solution d) 10% sodium chloride solution
In plants, long distance transport of organic and inorganic substances occur through
a) Simple permanent tissues
b) Complex permanent tissues
c) Meristematic tissues
d) Epithelial tissues
Xylem sap is made up of
a) Water alone b) Water and minerals c) Minerals alone d) Sugar and water
Passive absorption of mineral salts is not dependent on
a) Diffusion b) Osmosis
c) Donnan equilibrium d) Ionic exchange

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The pressure exerted by the protoplast due to the entry of water against the rigid cell wall is termed as
a) Turgor pressure b) Osmotic potential c) Solute potential d) Water potential
In the given schematic diagram, pathway of water movement inside the root is shown from soil to xylem.
Identify the tissue involved in the steps 𝐴-𝐶 and choose the correct option accordingly a) A-Hypodermis, B-Medullary rays, C-Metaxylem
b) A-Cortex, B-Pericycle, C-Metaxylem
c) A-Pericycle, B-Cortex, C-Metaxylem
d) A-Hypodermis, B-Cortex, C-Vascular tissues
Some statements are given regarding the active transport in plants. Choose the incorrect statement
a) Active transport need energy to pump molecules
against the concentration gradient
b) It is carried out with the help of membrane
protein
c) Due to more concentration of charged particles in
soil then the concentration in roots, active
absorption of mineral takes place
d) All of the above
Root endodermis has the ability to actively transport ions …A… because of …B… .
Choose the correct pair
a) A-bidirectionally; B-plasmodesmata b) A-undirectionally; B-casparion strips
c) A-undirectionally; B-plasmalemma d) A-bidrectionally; B-casparion strips
The shape of guard cells in stomata in sugarcane plant is
a) Dumb bell-shaped b) Bean shaped c) Horse shoe shaped d) Irregular shaped
Plants develops force for upward conduction of water against gravity is derived from
a) Photosynthesis process b) Transpiration
c) Root pressure d) Both (b) and (c)
How translocation of organic material is explained in plants?
a) By transpiration pull/cohesion adhesion theory
b) Imbibition theory
c) Mass flow hypothesis
d) Root pressure theory
Two cell (A and B) have osmotic potential and pressure potential – 18 bars and 8 bars, and – 14 bars and 2
bars respectively. What will be the direction of water flow?
a) From cell A to cell B b) Flow of water does not takes place
c) In both direction d) From cell B to cell A
Which one of the following acts as a barrier in a apoplastic pathway?
a) Epidermis b) Plasmodesmata c) Casparian strips d) Metaxylem
Go through the following pairs and choose the correct pairs from the option given below
I. Nerium Sunken lower epidermis of leaves to
stomata reduces loss of water
II. Calotropis Non-succulent Root cells with thickened
cell walls
III. Peperomia Leaf succulent Leaf epidermal cell, store
water
IV. Ammophila Dicot Curl their leaves to minimise
loss of water
V. Tribulus Ephemeral Water is stored in stem
a) All pairs are correct b) I, II and III are correct pairs
c) IV and V pairs are correct d) I, IV and V are correct pairs only

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Which pathway applies least resistance to the movement of water?
a) Apoplast pathway
b) Symplast pathway
c) Trans membrane pathway
d) Vacuolar pathway
Examples of bulk flow by a positive hydrostatic pressure gradient and a negative hydrostatic pressure
gradient are
a) Suction through straw and swelling of wood, respectively
b) Imbibition and a garden hose
c) Garden hose and suction through a straw, respectively
d) Swelling of wood and imbibition, respectively
During flowering, fruit ripening and development period in plants, which part of the plant act as source?
a) Whole plant
b) Stem and leaves and the plant
c) Photosynthesising leaves and older leaves
d) Growing parts of the plants
Plants growing on hills are likely to show
a) Higher rates of transpiration
b) Lower rates of transpiration
c) Same rate of transpiration as in plains
d) Lower rates of transpiration provided the stomata are sunken
The transport of ions up the stem to all parts is through
a) Transpiration stream b) Mass flow c) Diffusion d) None of these
How much of absorbed water is lost during transpiration in a plant?
a) 99% b) 98-99% c) 99.9% d) 90-95%
Which one of the following is part of symplast?
a) Cytoplasm b) Protoplast c) Plasmodesmata d) All of these
The real forces responsible for the movement of water from one cell to another cell is mainly
a) Osmotic pressure b) Turgor pressure
c) Diffusion pressure deficit d) Imbibitions
Water occur freely in previous rocks and deep in soil above the impermeable strata is
a) Ground water b) Soil water c) Deep stratum water d) Hygroscopic water
A twig kept in water having some salt remains fresh for longer period due to
a) Decrease in bacterial degradation b) Exosmosis
c) Decrease in transpiration rate d) Absorption of more water
If stem of plant is cut under a state of tension in xylem sap, what will be the result?
a) The xylem sap sprout out b) Xylem sap will accumulate at cut surface
c) The cut surface will form air bubbles, when placed
in water
d) Air will be pulled into the xylem
One factor responsible for water rise up to 100 m of tall plant, is
a) Root pressure b) Transpiration pull c) Pulsation d) Diffusion
Read carefully the following statements and choose the right answer from the options given below
I. Diffusion is a slow process and it do not depends upon the living system
II. Usually process of diffusion does not need energy
III. Diffusion can occur from one part of a cell to another part of the same cell or from one cell to another
and from one tissue to another tissue
IV. Diffusion is a rapid process over short distance, but extremely slow over long distances
a) I and III b) I and II c) III and IV d) I, II, III and IV
Tension, one of the important factor in the movement of xylem sap in a tree is a result of

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a) Cohesive nature of water b) Capillary size of xylem tube
c) Transpiration at the leaf surface d) All at the above

What is the approximate dry weight contained by majority of herbaceous plants?
a) Ground 50% of fresh weight b) 31% of fresh weight
c) About 10-15% of fresh weight d) Exactly 29% of dry weight
Root hair absorb water from the soil on account of
a) Turgor pressure b) Osmotic pressure c) Suction pressure d) Root pressure
The space between the plasma membrane and the cell wall of a plasmolyzed cell surrounded by a
hypertonic solution is occupied by the
a) Hypotonic solution b) Isotonic solution c) Hypertonic solution d) Water
The first process by which water enters into the seed coat when a seed is placed in suitable
environment for germination is
a) Osmosis b) Active transport c) Absorption d) Imbibitions
The osmotic potential and pressure potential of three cells (A, B, C) located in different parts of an
actively transpiring plant are given below.
Cell Osmotic
Potential
(MPa)
Pressure
Potential
(MPa)
A -0.87 0.44
B -0.92 0.34
C -0.68 0.27
Identify these three cells as root hair, root cortical and leaf mesophyll cells respectively. The
correct answer is
a) A, B, C b) A, C, B c) C, A, B d) B, C,A
In tall plants, because of which factor, continuous water column extends upward?
a) Atmospheric pressure b) Osmotic pressure
c) Suction pull d) Root pressure
In the given diagram identify the marked phenomenon/part and choose the correct option accordingly a) A-Phloem, B-Sugar leaves sieve tube, C-Sugar enters sieve tube
b) A-Xylem, B-Sugars leaves sieve tube, C-Sugar enters sieve tube
c) A-Phloem, B-Sugar enters sieve tube, C-Sugars leaves sieve tube
d) A-Xylem, B-Sugar enters sieve tube, C-Sugars leaves sieve tube
What will happen, if a large amount of water enters in a plant cell?
a) TP of cell gets reduced b) TP opposes the entry of water
c) Water potential of the cell become more negative d) Water potential of the cell increases
simultaneously
Identify true and false statements and select the correct option from the codes given below
I. As suction pressure increases, water absorption also increases which in turn increases the absorption of
ions

Page| 14

II. Absorption of ions is affected by transpiration pull
III. Large amount of charged particles are absorbed along with absorption of water
IV. Pressure flow hypothesis depends entirely on the existence of mechanism for loading sugars into
phloem at the source region and unloading it at the sink
V. Contents in the sieve tube move undirectionally
a) I, II, III and IV are true while V as false b) I, III, IV and are true while II is false
c) I, II, IV and V are true while III is false d) II, III, IV and V are true while I is false

Opening of stomata is not affected by
a) N2 b) K+ ions c) Starch d) None of these
Osmosis involves flow of
a) Water without a membrane
b) Solute from a semi-permeable membrane
c) Solvent (H2O) through a semi-permeable membrane
d) None of the above
Cohesion force, a feature of cohesion theory is also called
a) Tensile a strength b) Surface tension c) Mutual force d) Transpiration pull
A plant cell becomes turgid due to
a) Plasmolysis b) Exosmosis c) Endosmosis d) Electrolysis
Which of the following experiments is called physiological demonstration of osmosis?
a) Thistle funnel, whose mouth is tied with egg membrane
b) Thistle funnel, whose mouth is tied with parchment paper
c) Photometer
d) Bell jar experiment
Which of the following statements is/are true?
I.The apoplastic movement of water occurs exclusively through the cell wall without crossing any
membranes.
II.Solutes present in a cell (or in any solution) increase the free energy of water or water
potential.
III.The symplastic movement occurs from cell to cell through the plasmodesmata.
IV.Membrane permeability depends on the membrane composition, as well the chemical nature
of the solute.
a) I and II only b) II and Iv only c) I, III and IV only d) I, II and IV only
Which of the following maintains the shape of cell?
a) Osmotic pressure b) Turgor pressure c) Wall pressure d) Osmosis
Consider the following statements and choose the correct answer
I. Carrier proteins are needed by both facilitated diffusion and active transport and are sensitive to
inhibitors that react with protein side chain
II. Different types of proteins present in the membrane plays a major role in both active as well as passive
transport
III. The carrier proteins needed by facilitated and active transport are specific
IV. There is no need of energy to pump molecule against a concentration in active transport
V. Transport rate reaches to saturation point, when all the active proteins are used
a) I, II, II, IV and V b) I, II and III c) V, IV and I d) I, II, III and V
Root hair absorbs water from soil through
a) Turgor pressure b) Ion exchange c) Osmosis d) DPD
Which type of soil has least water retaining capacity?
a) Sandy soil b) Black or alluvial soil c) Laterite soil d) Loan soil

Page| 15

Phloem sap is mainly ….. and ….. . Choose the correct pair of options?
a) Water, sucrose b) Sugars, water c) Sucrose, sugars d) Amino acids, sugars
Passive absorption of water by the root system is the result of
a) Forces created in the cells of the root b) Increased respiratory activity in root cells
c) Tension on the cell sap due to transpiration d) Osmotic force in the shoot system
The rate if diffusion is dependent upon the permeability of the medium, it however
a) Influences the final equilibrium of diffusion as it is never reached if the medium is dense
b) Does influence the final equilibrium of diffusion
c) Does not influence the final equilibrium of diffusion
d) None of the above
If flowers are cut and dipped in dilute NaCl solution, then
a) Transpiration is low
b) Endosmosis occurs
c) No bacterial growth takes place
d) Absorption of solute inside flower cell takes place
Munch hypothesis is based on
a) Translocation of food due to TP gradient and imbibition force
b) Translocation of food due to turgor pressure (TP) gradient
c) Translocation of food due to imbibition force
d) None of the above
Study the following table showing the components of water potential in closely arranged
mesophyll cells namely A, B and C.
Cell Osmotic
Potential
(MPa)
Pressure
Potential
(MPa)
A -0.21 0.05
B -0.22 0.02
C -0.23 0.05
Identify two of the following, which show correct direction of water movement between two cells.
I A→B II B→C
III C→A IV C→B
a) I, II b) II, III c) I, IV d) II, IV
Transpiration facilitates
a) Electrolyte balance b) Opening of stomata
c) Absorption of water by roots d) Exertion of minerals
Which of the following is not correct regarding carrier molecules, involved in facilitated diffusion?
a) They are responsible to concentrate solute molecules on the side of membrane
b) They are responsible to increase the speed of transport across a membrane
c) They may be under conformational change upon binding of solutes
d) They possess specific binding sites for molecules to be transported
Which of the following is used as an antitranspirant?
a) Cobalt chloride b) Naphthol acetic acid
c) Calcium carbonate d) Phenyl mercuric acetate
Study the following statements
I. Most minerals must enter the roots by active absorption into cytoplasm and epidermal cells
II. Ions are absorbed by both passive and active transport
III. Active absorption does not require energy

Page| 16

IV. Active uptake of ions is responsible for osmosis
Choose the correct option in reference to the statements given above
a) I and II are correct and III and IV are incorrect b) I, II and IV are correct and III is incorrect
c) I, II, III and IV d) I, III and II are correct IV is incorrect

Arrange the following events of mass flow of organic material in sequence
I. Sugars are transported from cell to cell in the leaf
II. Food is synthesised in form of glucose by leaf cells
III. Movement of water takes place into sieve tube elements
IV. Downward movement of sugar occurs in the stem
V. Solutes are actively transported into the sieve elements
a) I, II, III, V, IV b) II, I, V, III, IV c) II, III, I, V, IV d) I, II, V, IV, III
Which of the following lacks stomata?
a) Aquatic plants with floating leaves b) Xerophytes
c) Aquatic submerged plants d) Sciophytes
Guard cells control
a) Intensity of light entering b) Photosynthesis
c) Closing and opening of stomata d) Change in green color
Wilting occurs when
a) Rate of transpiration is higher than absorption
b) Rate of absorption is higher than transpiration
c) Excess root pressure
d) High relative humidity in air
Which among the following represents the correct relationship for a plasmolysed cell?
a) ΨW=ΨS+ΨP b) ΨS=ΨW+ΨP c) ΨW=ΨS d) ΨW=ΨP
Water in the soil available to plants is
a) Gravitational water b) Capillary water c) Hygroscopic water d) None of these
If two types of seeds, like pea and maize are kept in water at the same time. Which among the two will
imbibe more water?
a) Maize seed
b) Pea seed
c) Both imbibe equal amount of water
d) Pea seed imbibe more water only at alkaline pH
The magnitude of root pressure ranges between
a) 2-5 atm b) 1-5 atm c) 0.1-0.2 atm d) 4-6 atm
Read the following statements regarding porins and select the correct option given below
I. Porins are transport proteins
II. Channel proteins are a type of transport protein, which are usually gated
III. Carrier protein binds the particular solute to be transported
IV. Particular solute is delivered to the other side of the membrane by carrier proteins
a) I, II and III b) I, III and IV c) I, II, III and IV d) I and IV
RBC and a plant cell (with thick cell wall) are placed in distilled water. The solute concentration is
the same in both the cells. What changes would be observed in them?
a) Both plant cell and RBC would not undergo any change
b) The RBC would increase in size and burst, while the plant cell would remain about the same
size
c) The plant cell would increase in size and burst, while the RBC would remain about the same
size
d) Both plant cell and RBC would decrease in size and collapse

Page| 17

Osmotic pressure is highest in which of the following plant type?
a) Mesophytes b) Xerophytes c) Halophytes d) Hydrophytes
When a cell is plasmolysed, it becomes
a) Flaccid and its TP becomes zero b) Turgid and its becomes zero
c) Turgid and TP becomes equal to OP d) Flaccid and DPD becomes zero
Water is lost in a liquid state in some plants through hydathodes. These hydathodes
a) Remain closed at night
b) Remain closed during day
c) Remain always open
d) Do not show any specificity in opening and closing
Cell-A has osmotic potential of -18 bars and pressure potential of 8 bars, whereas, cell-B has
osmotic potential of -14 bars and pressure potential 2 bars. The direction of flow of water will be
a) From cell-B to cell-A b) From cell-A to cell-B
c) No flow of water d) In both the directions
Which type of transpiration continues throughout day and night?
a) Cuticular transpiration b) Lenticular transpiration
c) Bark transpiration d) All of these
The first process responsible for the entry of water into a seed, when it is placed in a suitable environment
for germination is
a) Absorption b) Imbibition
c) Active transport d) Osmosis and diffusion
Read the given statements regarding the different stages of plasmolysis and choose the correct option
I. First stage of plasmolysis, when osmotic concentration of cell sap is just equivalent to that of external
solution
II. Protoplast withdraws itself from corners of the cell wall
III. Protoplast gets detached from the cell wall and attains a spherical shape
I II III
a) Incipient Limiting Evident
plasmolysis plasmolysis plasmolysis
b) Limiting Incipient Evident
plasmolysis plasmolysis plasmolysis
c) Limiting Evident Incipient
plasmolysis plasmolysis plasmolysis
d) Evident Incipient Limiting
plasmolysis plasmolysis plasmolysis
Water composition in a water-melon is approximately
a) 95% b) 97% c) 90% d) 92%
The membrane, which allows passage of certain substances more readily than others is termed as
a) Permeable b) Selectively permeable
c) Semi-permeable d) Impermeable
Which one of the following is not a part of symplast?
a) Cell wall b) Plasma membrane
c) Plasmodesmata d) Cytoplasm
What is mandatory in the process of facilitated diffusion?
a) Presence of concentration gradient b) A carrier protein
c) A hydrophilic moeity d) All of the above
A special type, which occurs when water is absorbed by solids causing them to increase in volume is called
a) Osmosis b) Translocation c) Imbibition d) Transpiration

Page| 18

Which of the following does not affect water potential of water?
a) Concentration of dissolved substances b) Atmospheric pressure
c) Gravitation d) Capillarity
Study the following pairs.
VI. Peperomia Leaf succulent Leaf epidermal cells store water.
VII. Calotropsis Non-succulent Root cells with thickend cell walls.
VIII. Tribulus Ephermeral Stem stores water.
IX. Ammophila Dicot plant Rolling in of leaves to check water loss
Identify the correct pair of answer.
a) I, II b) I, III c) II, III d) II, IV
Consider the following statements and choose the correct option from codes given below
I. Loading of phloem is related to increase of sugar in phloem
II. Active loading of sugar in sieve tube of phloem is driven by proton pump
III. Pressure may be positive or negative in sieve tube cells
IV. Water and solutes move through the sieve tube against pressure gradient
V. Cytoplasmic strand passes through the holes in sieve plates and form continuous filaments
a) I, II, V are incorrect, while III and IV are correct
b) III and IV are incorrect while I, II and V are correct
c) I, II and III are incorrect while IV and V are correct
d) IV and V are incorrect while, I, II and III are correct
Path of water movement from soil to xylem is
a) Soil→root hair→cortex→pericycle→endodermis→metaxylem→protoxylem
b) soil→root hair→cortex→endodrmis→pericycle→protoxylem→metaxylem
c) soil→root hair→epidermis→endodermis→phloem→xylem
d) soil→root hair→epidermis→cortex→phloem→xylem
The stomata in CAM plants open during
a) Day b) Night c) Day and night d) Always closed
What will be the affect of accumulation of potassium ions in guard cells?
a) Decrease in turgor pressure b) Exosmosis
c) Increase in water potential d) Decrease in water potential
Through which process, starch of the guard cell is converted into PEP ions?
a) Dephosphorylation b) Decarboxylation c) Hydrolysis d) Oxidation
Which one of the following does not help in molecular transport?
a) Diffusion b) Osmosis c) Surface tension d) Active transport
Ascent of sap is
a) Active and requires energy expenditure by the soil b) Passive, and no requirement of energy by the
plants
c) Active and requires energy expenditure by the
plants
d) Passive unless soil is dry
Passage cells are thin-walled cells found in
a) Endodermis of roots facilitating rapid transport of water from cortex to pericycle
b) Phloem elements that serve as entry points for substances for transport to other plant parts
c) Testa of seeds to enable emergence of growing embryonic axis during seed germination
d) Central region of style through which the pollen tube grow towards the ovary
The term apoplast signifies
a) Cell wall, intercellular space and water filled
channel
b) Protoplasts inter connected by plasmodesmata
c) Cell wall, cytoplasm and central vacuole d) None of the above

Page| 19

Select the correct option in reference with the statements given below
I. Facilitated diffusion cannot cause net transport
II. Transport rate in case of facilitated diffusion never reaches to a maximum level
III. Facilitated transport is selective to inhibition proteins
IV. Concentration gradient is not required in case of facilitated diffusion
a) II and IV b) I, II, III and IV c) I and III d) None of these
Osmotic pressure of a solution is
a) Greater than pure solvent b) Less than pure solvent
c) Equal to pure solvent d) Less than or greater than pure solvent
Potometer works on the principle of
a) Amount of water absorbed equals the amount transpired
b) Osmotic pressure
c) Root pressure
d) Potential difference between the tip of the tube and that of the plant
In which of the following path, flow of water occurs from cell to cell through their protoplasm?
a) Apoplast pathway b) Symplast pathway
c) Both (a) and (b) d) Transmembrane pathway
Transport of minerals through xylem is
a) Active and energy is provided by ATP b) Passive and no energy is provided
c) Active and no requirement of energy d) Passive and energy is provided by ATP
Mechanism of opening and closing of stomata is controlled by
a) Guard cells b) Accesary cells c) Epidermal cells d) None of these
Stomata are also called as
a) Stomates b) Lenticels c) Hydathodes d) Bark
Identify the following process and choose the correct option a) Simple diffusion b) Facilitated diffusion c) Osmosis d) Deplasmolysis
The diagram given below represents the simple ringing or girdling experiment. Bark containing phloem is
removed. This experiment proves and justify that phloem is the path for translocation of food. In the given
diagram, swollen part of stem has been indicated. What is cause of swollen part?

Choose the correct option
a) Accumulation of food material just above the ringing space
b) Accumulation of minerals and water just above the ringing space
c) A repairing mechanism is taken
d) Injured part undergo turgor change

Hydathodes are also called
a) Water stomata b) Sunken stomata c) Guard cells d) Subsidiary cells

Page| 20

What happens when concentration of solutes decreases in guard cells?
a) Water potential increases b) Osmotic pressure increases
c) Water potential decreases d) None of the above
During water absorption from the soil, the water potential of the root cell is…..than the soil
a) Higher b) Lower c) Slightly higher d) Slightly lower
Water potential gradient can be best defined as
a) Pressure gradient minus water potential
b) The overall movement of water
c) Evaporation of water from stem and leaves
d) The overall movement of solutes
Humidity in atmosphere decreases rate of
a) Transpiration b) Photosynthesis c) Glycolysis d) Growth
Guard cells help in
a) Protection against grazing b) Transpiration
c) Guttation d) Fighting against infection
Both minerals and water are absorbed by
a) Zone of elongation in root
b) Growing point in root
c) Root hair zone
d) Zone of mature cells
Fensom and Jones suggested which of the following method for translocation of solute?
a) Osmosis b) Plasmolysis c) Diffusion d) Electrosmosis
Mycorrhiza, a mutal relationship between fungus and a root of gymnosperm helps in
I. absorption of water
II. mineral absorption
III. translocation
IV. gaseous exchange
Choose the correct option
a) Only I b) II and I c) III and IV d) Only II
Which of the following pair is selective and specific mode of transport?
a) Passive transport and active transport
b) Passive transport and facilitated diffusion
c) Facilitated diffusion and active transport
d) Simple diffusion and facilitated diffusion
Consider the following statements and choose the correct answer from the options given below
I. A dry live seed still contains water
II. A mature maize plant absorbs about 3 L water per day
III. A mustard plant take up water equal to its weight in about five hours
IV. Water is not considered as the limiting factor for plant growth and productivity
a) I, II, III and IV b) IV and II c) I, II and III d) Only IV
Which one is true about guttation?
a) It occurs through specialized pores called hydathodes
b) It occurs in herbaceous plants when root pressure is low and transpiration is high
c) It only occur during the day time
d) It occurs in plants growing under conditions of low soil moisture and high humidity
What are the location of casparian strips-which interrupts the movement of water inside a root?
a) Endodermis b) Pericycle c) Cortex d) Hypodermis
Select the correct statement from the following

Page| 21

a) Only the net direction of osmosis, not the rate of osmosis depends on both the pressure gradient and
concentration gradient
b) The rate of osmosis depends only on pressure gradient
c) The net direction and rate of osmosis depends upon both the pressure gradient and concentration
gradient
d) The net direction and rate of osmosis do not depend on the pressure gradient and concentration
gradient

Which one of the following doesn’t help in molecule transport?
a) Diffusion b) Osmosis c) Surface tension d) Active transport
What type of material do not diffuse or find it difficult to pass through the membranes?
a) Hydrophobic substance
b) Hydrophilic substances
c) Inorganic solute
d) Both hydrophilic and hydrophobic substances
When the concentration of the soil solutes is low, the absorption of water
a) Remains normal b) Is stopped c) Is increased d) Is decreased
If sugars are actively moving into a cell, what will happens to the turgor pressure of the cell?
a) TP increases, due to the entry of water
b) TP decreases because water exits
c) TP increases as sugar concentration affects it directly
d) No effect of sugar concentration of furgidity hence no change
Read the following statements and choose the correct answer from the options given below
a) In the absence of casparian strips, plants are unable to control amount of water and solute it absorbs
b) Guttation is generally occur during low atmospheric humidity and plentiful soil water
c) Role of Na+ in stomatal opening is universally accepted
d) In CAM, plant stomatal remains open in day and night
Movement among cells against concentration gradient is called
a) Osmosis b) Active transport c) Diffusion d) Passive transport
Transport proteins of endodermal cells are …A… where a plant adjusts the …B… and …C… of solutes that
reaches the …D…
Choose the correct combination of A-D from the given options
a) A-control points, B-ratio, C-type, D-xylem
b) A-regulators, B-quantity, C-type, D-phloem
c) A-control points, B-quantity, C-type, D-xylem
d) A-regulators, B-quantity, C-size, D-phloem
Select the correct events leading to the opening of the stomata.
I.Decline in guard cell solutes.
II.Lowering of osmotic potential of guard cells.
III.Rise in potassium levels in guard cells.
IV.Movement of water from neighbouring cells into guard cells.
V.Guard cells becoming flaccid.
a) I and V b) II, III and IV c) I, III and IV d) II, IV and V
Choose, true and false statements from the following and select the correct option from the set (a-d) given
below
I. Diffusion is an important process of transport in plants since it is the only means for gaseous movement
within the plant body
II. In active transport, pumps are proteins that use energy to carry substance across the cell membrane
against concentration gradient

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III. In facilitated diffusion, special proteins helps hydrophilic substances to be transported across the
membrane
IV. In diffusion, molecules move against concentration gradient in a random manner
V. Facilitated diffusion is faster than active transport
a) I, II, III and IV b) I, II, III are true, while IV and V are false
c) IV and V are true, while I, II and III are false d) Only II, III, IV are true while I and V are false

Which one of the following is the most accepted theory of ascent of sap?
a) Root pressure theory b) Root pressure theory c) Passive transport d) Cohesion theory
At the time of seed germination, when water is absorbed by the seed due to imbibition, the seed coat
breaks as it swells to a lesser degree than the kernel because
a) The kernel is made up of cellulose while the seed
coat is made up of proteins lipids and starch
b) The kernel is made up of proteins, lipids and
starch, while the seed coat is formed of cellulose
c) Both kernel and seed coat are made up of same
constituents, it depends on the nature of medium
d) None of the above
Unloading of minerals occur at
a) Apical meristem b) Fine vein ending c) Fruits d) All of these
Why the tropical deciduous forest trees shed their leaves?
a) To save energy b) To protect itself from chat
c) To enhance rate of respiration d) To prevent loss of water
Which of the following affects the rate of diffusion?
a) Concentration gradient b) Permeability of the membrane
c) Temperature and pressure d) All of the above
A student has taken a twig from a plant. She/he observe a droplet of fluid exuding from the cut surface of
twing. What is this fluid?
a) Plant latex b) Phloem sap c) Xylem sap d) Both (b) and (c)
The translocation of organic solutes in sieve tube members is supported by
a) Root pressure and transpiration pull b) P-proteins
c) Mass-flow involving a carrier and ATP d) Cytoplasmic streaming
Active transport
a) Releases energy b) Requires energy
c) Produces ATP d) Produces a toxic substance
Some cells are placed in a solution of glucose to measure the rate of diffusion. As the concentration of
glucose solution is being increased, the diffusion rate increases simultaneously. However, when the
concentration of glucose solution reaches above 10 m, the diffusion rate no longer increases
Which statement best define the mechanism of glucoses transport in the cells?
a) Transport of hydrophilic substances along the concentration gradient through fixed membrane
transport protein without the involvement of energy expenditure
b) Transport of hydrophilic substances along and against the concentration gradient via carrier proteins
c) Active transport via transporter proteins
d) Facilitated diffusion without carrier proteins
The plants, which are able to send their roots up to the fringe of water table are called
a) Xerophytic plants b) Terrestrial plants c) Phreatophytes d) Mesophytes
Transport of different types of solute substances takes place by
a) Bulk flow system b) Combind response c) Facilitated diffusion d) Pressured transport
Phloem sap is made up of
a) Water and minerals b) Water and sucrose c) Water and glucose d) Both (b) and (c)
Which of the following affect the transport of molecules when carrier mediated facilitated diffusion is
involved?
a) Solubility of molecule in lipids b) Concentration gradient

Page| 23

c) Availability of carrier molecule d) All of the above

Who coined the term diffusion pressure deficit?
a) Slatyer b) Taylor c) Meyer d) Slatyer and Taylor
Which one of the following does not play a major role in upward movement of xylem sap in tall trees?
a) Transpiration b) Tension
c) Cohesion and Adhesion d) Plasmodesmata
Why the rate of diffusion of a substance along the concentration gradient does not increase continuously,
while the concentration difference of the molecules across the membrane increases?
a) Process of facilitated diffusion need ATP
b) As concentration difference increases, molecule interfere with one another
c) 100% saturation of carrier protein after some time
d) Transport proteins must be of channel protein type
Which of them is/are correct regarding pressure flow model for translocation?
I. Sugar is transported through phloem as glucose
II. Movement of sugar is carried out through sieve tube near the source region
III. Concentration of sugar is always highest near the sink region
IV. Water from the adjacent xylem moves into phloem by osmosis
a) II and IV b) II and III c) I, II and III d) Only IV
After heavy rain fall with poor drainage, laves of many plants wilt due to
a) Root rot
b) Poor aeration
c) High salt concentration
d) Low soil temperature
Graham’s law is correlated with
a) Diffusion b) Osmoregupation c) Osmosis d) Absorption
Who proposed the ‘Cohesion Theory’ of ascent of sap?
a) Strasburger b) Godlewski c) Western d) Dixon andJolly
Which of the following statements is/are not true?
I.In CAM plants, stomata open during dark and remain closed during the day.
II.Role of Na+ in stomatal opening is now universally accepted.
III.The water potential of root cells is higher than the water potential of soil.
IV.Capillarity theory is the most accepted theory of water movement through plants.
V.The walls of xylem vessels made up of lingo-cellulose have strong affinity for water molecules.
a) II, III and V b) II, III and IV c) I, II and III d) II and III
How would you differentiate between apoplast and symplast?
a) Apoplast relies on active transport
b) Symplast deals in non-living spaces and cell walls
c) Apoplast prevents passive diffusion
d) Apoplasts deals in non-living spaces and cell walls
Water potential of a solution is denoted by
a) ΨX b) ΨP c) ∆Ψ d) Ψ𝑤
Which one of the following statements is wrong?
a) Water potential is the chemical potential of the water
b) Solute potential is always negative
c) Pressure potential is zero in a flaccid cell
d) Water potential equals solute potential in a fully turgid cell
Cell wall present in water conducting tissues, represented by swollen nodules, is known as
a) Tertiary wall b) Middle lamella c) Plasmalemma d) Primary cell wall

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Transport of organic solutes is supposed to take place by pressure flow hypothesis through phloem tissue
from source to sink. Choose the false statement about vascular tissue transport
a) Phloem transport mainly water and sucrose but other sugars, hormone and aminoacids are also
transported
b) Water enters into the sieve tube by the process of osmosis
c) Water and solute move through the sieve tube along the pressure gradient
d) Sieve tube in the source have a low turgor pressure (pressure potential)
How much percentage of absorbed water in plants is used in the process of photosynthesis?
a) Around 0.2% b) Less than 1% of absorbed water
c) 1% of absorbed water d) 1-2% of absorbed water
The force responsible for upward conduction of water against gravity comes from
a) Transpiration b) Photosynthesis c) Translocation d) Respiration
Which of the following is not a purpose of transpiration?
a) Supplies water for photosynthesis
b) Helps in translocation of sugars from source to sink
c) Maintains shape and structure of the plant
d) Cools leaf surface
A soil sample is found to have 25% of its volume occupied by soil water. Of this, 10% is
hygroscopic water and the remaining is capillary water. What is the field capacity of this soil?
a) 10% b) 15% c) 25% d) 35%
Why is active transport considered important?
a) Because material is transported from higher
concentration to lower concentration
b) Because material is transported from lower
concentration to higher concentration
c) Because it increases diffusion coefficient d) Because it does not use ATP
In mycorrhizal association, which one of the following increases the surface area available for absorption
of water and minerals by roots?
a) Mycorrhiza
b) Numerous branches of root
c) Root hairs
d) None of the above
Uphill transport is a type of
a) Active transport b) Passive transport c) Facilitated diffusion d) Simple diffusion
Compare the following processes of transport and choose the correct option
S.
No
.
Property Facilit
ated
Diffusi
on
Activ
e
Tran
sport
Simp
le
Diffu
sion
I. Highly
specific
Yes it
is
selecti
ve
Yes No
II. Energy
as ATP
Yes Yes Yes
III. Saturati
on point
is
attached
when all
carrier
protein
are
Yes No Yes

Page| 25

being
used
IV. Require
transpor
t
proteins
Yes No Yes

a) Only II
b) Only III
c) I, II, III and IV
d) Only I

Ascent of sap in plants was demonstrated by
a) Girdling experiment b) Ganong’s experiment
c) Went experiment d) Lever auxanometer
The value of pure water potential is
a) Always positive or more than zero
b) Always negative or less than zero
c) Always zero
d) Variable in different solution
Loss of water in liquid phase (in form of droplets) from the margin of leaves in many herbaceous plants is
a) Guttation b) Root pressure c) Transpiration d) Transpiration pull
The relationship among different types of soil water can be summed up of the following equation:
a) Chresard=Echard+Hollard b) Chresard=Hollard+Echard
c) Echard=Hollard+Chresard d) Hollard= Chresard–Echard
A cell dipped in 0.5 M sucrose solution has no effect but when the same will be dipped in 0.5 M
NaCl solution, the cell will
a) Increase in size b) Decrease in size
c) Will be turgid d) Will get deplasmolysed
Transpiration is manifestation of
a) Turgor pressure b) Wall pressure c) Root pressure d) None of these
Two cells A and B are contiguous. Cell-A has osmotic pressure-10 atm, turgor pressure-7 atm and
diffusion pressure deficit-3 atm. Cell-B has osmotic pressure-8 atm, turgor pressure-3 atm and
diffusion pressure deficit 5 atm. The result will be
a) Movement of water from cell-B to A b) No movement of water
c) Equilibrium between the two d) Movement of water from cell-A to B
Plasmolysis is the result of
a) Exosmosis b) Endosmosis c) Reverse osmosis d) Diffusion
Stomata open and close due to
a) Turgor pressure change b) Hormonal change
c) Temperature change d) All of these
Which one is incorrect statement?
a) Movement of water is expressed in terms of free energy
b) Free energy determines the direction by which physical and chemical changes should occur
c) Water potential is the sum of free energy of water molecules in pure water and in any other
system
d) Water potential of pure water is zero

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Which of the following is appropriate for mass-flow hypothesis?
a) Transpiration pull is responsible for absorption of ions
b) Large amount of ions are also absorbed along with the absorption of water
c) As suction pressure increases, absorption of water increases and along with water, absorption
of ion also increases
d) All of the above
The antitranspirant is
a) PMA b) ABA c) Both (A) and (B) d) None of these
The rupture and fractionation do not usually occur in the water column in vessles/tracheids
during the ascent of sap because of
a) Lignified thick walls b) Cohesion and adhesion
c) Wak gravitational pull d) Transpiration pull
The rate of diffusion of any substance is not affected by
a) Electrical charges of diffusing substances
b) Presence of other substances in the solution
c) Molecular size of substances in a solution
d) Solubility to diffusing substance in lipids
Cohension and adhension theory, is otherwise called
a) Relay pump theory b) Pulsation theory
c) Root pressure theory d) Transpiration pull theory
Stomata open due to accumulation of
a) K+ b) Na+ c) Mg+ d) Ca2+
Which of the following in guard cell is responsible for opening of stomata?
a) Decrease in CO2 concentration and more H+ ion concentration
b) Decrease in CO2 concentration and less H+ ion concentration
c) Increase in CO2 concentration and more H+ ion concentration
d) More free H+ ions and less Cl− ions
Which of the following is the most accepted theory for movement of water through plants?
a) Cohension theory b) Capillarity c) Passive transport d) Root pressure
The force responsible for the water movement against gravity even up to a 130 m of tall free comes from
a) Root pressure b) Transpiration pull c) Diffusion pressure d) Pulsation
A leaf with more stomata on lower surface belongs to
a) Potato type b) Oat type
c) Apple-mulberry type d) Nymphaea type
When a plant cell is placed in pure water, it
a) Expands until the osmotic pressure reaches that of water
b) Becomes less turgid until the osmotic potential reaches that of pure water
c) Becomes more turgid until the pressure potential of cell reaches its osmotic potential
d) Becomes more turgid until the osmotic potential reaches that of pure water
The loosely arranged non-chlorophyllous parenchyma cells present in lenticels, are called
a) Complementary cells b) Passage cells
c) Water stomata d) Albuminous cells
Select the wrong statement regarding membrane channels
a) They are proteins
b) They are usually gated, i.e., may be open or closed
c) All ions pass through the same type of channel
d) They form a huge pore in the outer membrane of plastids, mitochondria and some bacteria

Page| 27

A group of students are studying transport of certain type of molecules in a cells and observe that
transport slows down when the cells are treated with poison, a chemical, which inhibit energy production.
Under normal conditions, the molecules are being studied and it is estimated that molecules probably
transported by
a) Osmosis b) Process of active transport
c) Process of facilitated diffusion d) Process of simple diffusion
In symplast pathway of water movement, water passes from cell to cell, whose cytoplasm are connected
through
a) Plasma membrane b) Plasmodesmata c) Transmembrane d) Plasmalemma
Select the correct statement
a) Water can be absorbed passively by roots
b) Ions are generally absorbed from soil by both active and passive transport
c) C4 photosynthetic system is evolved for maximising the availability of CO2 and to minimise loss of
water
d) All of the above
Which ion helps in opening and closing of stomata?
a) Mn+ b) Mg2+ c) Ca2+ d) K+
Which theory is considered best to explain ascent of sap
a) Bulk flow system b) Transpiration pull c) Transpiration d) Root pressure theory
Which of the following get accumulated in the vacuoles of guard cells during stomatal opening?
a) Water, calcium and magnesium b) Starch, potassium and chloride ions
c) Malate, sodium and potassium ions d) Malate, potassium and chloride ions
Transpiration is the manifestation of
a) Root pressure b) Turgor pressure c) Wall pressure d) Suction pressure
Which among the following has highest water potential?
a) 1 m salt solution b) 1 m glucose solution c) Distilled water d) Both (a) and (b)
Stomatal opening is affected by
a) Nitrogen concentration, carbon dioxide concentration and light
b) Carbon dioxide concentration, temperature and light
c) Nitrogen concentration, light and temperature
d) Carbon dioxide concentration, nitrogen concentration and temperature
Stoma opens, when
a) Guard cells swell due to an increase in their water potential
b) Guard cells swell by endosmosis due to influx of hydrogen ions (protons)
c) Guard cells swell by endosmosis due to efflux of potassium ions
d) Guard cells swell due to a decrease in their water potential
If solute particles are added in pure water, its diffusion pressure will be
a) Increased b) Decreased
c) Remain constant d) Become less than zero
A red blood cell (RBC) was kept in a certain solution for few minutes and it got burst. The said
solution was
a) Isotonic b) Concentrated sugar solution
c) Hypertonic d) Hypotonic
The rate of transpiration will be very less in a situation where
a) Ground water is sufficiently available b) Wind is blowing with a very high velocity
c) Environment is very hot and dry d) Relative humidity is very high
The factor, most important in regulating transpiration, is
a) Temperature b) Light c) Wind d) Relative humidity

Page| 28

Wooden doors and logs swells up, and get stuck up during rainy season due to
a) Imbibition b) Endosmosis c) Exosmosis d) Both (a) and (c)
If water enters in a cell, the pressure exerted by its swollen protoplast is
a) Turgor pressure b) DPD c) Osmotic pressure d) Imbibition
What is the most efficient region of water absorption in roots?
a) Root cap b) Growing point
c) Zone of elongation d) Zone of differentiation
Regarding root pressure, which one is not correct?
a) It is sufficient to rise water above ground level
b) It is positive in all except the tallest trees
c) It do not act as driving force for the mass flow of sugar
d) It is not able to push water up to small height in the stem
Choose the correct statements regarding guttation and pick the correct option from the codes given below
I. It occurs through specialised pore called hydathode
II. Hydathodes can be located on the margin and tips of leaves
III. It occurs in plants growing under condition of low soil moisture and high humidity
IV. It occurs in herbaceous plants when root pressure is low and transpiration is high
a) I and II b) III and IV c) I, II, III and IV d) I, II and IV
What is the value of DPD?
a) DPD = TP b) DPD = OP – SP
c) DPD = OP – WP d) Equal to wall pressure
The transport of organic and inorganic substances in plants over longer distance occurs through vascular
tissue by the means of
a) Diffusion
b) Facilitated diffusion
c) Active transport
d) Mass flow
Choose the correct statement regarding casparian strips
I. It surrounds pericycle
II. It is made up of legnosuberin
III. It limits the pathway available to water solutes, forcing them to enter the symplast
a) I and III b) I, II and III c) 1 and II d) None of these
Translocation of organic materials in plants is explained
a) Active transport b) Transpiration pull
c) Inhibition theory d) Mass-flow hypothesis
Choose the correct option given below
a) Diffusion needs ATP
b) Diffusion is an active and rapid process
c) Diffusion is rapid over short distance but extremely slow over long distance transport
d) Diffusion is slow over short distance, but rapid over long distance transport
Movement of water through cell wall, is
a) Apoplast b) Symplast c) Tonoplast d) None of these
Adhesion is caused by
a) Formation of hydrogen bond between water
molecules
b) Transpiration pull
c) Higher surface tension d) Attraction of water molecule to polar surface
Short distance transport of substances like nutrients, water etc., in plants occur through
a) Diffusion
b) Cytoplasmic steaming supplemented by active transport

Page| 29

c) Both (a) and (b)
d) Passive transport only

A portion of transverse section of root is shown in the diagram. Label A-H in the given diagram and choose
the correct option accordingly a) A-Apoplastic, path; B-Symplastic, path; C-Endodermis; D-Pholem; E-Cortex; F-Casparian strip; G
Pericycle; H-Xylem
b) A-Symplastic, path; B-Apoplastic, path; C-Xylem; D-Pholem; E-Endodermis; F-Cortex; G-Casparian strip;
H-Pericycle
c) A-Symplastic, path; B-Apoplastic, path; C-Endodermis; D-Xylem; E-Cortex; F-Casparian strip; G
Pericycle; H-Phloem
d) A- Apoplastic, path; B-Symplastic, path; C-Endodermis; D-Cortex; E-Casparian strip; F-Xylem; G-Phloem;
H-Stele
With the increase in temperature, the process of imbibition
a) Decreases b) Increases c) Remains the same d) No effect
In which form, does the food transported in plants?
a) Sucrose b) Fructose c) Glucose d) Lactose
Identify the correct relationship with reference to water potential of a plant cell.
a) Ψw=Ψm+Ψs+Ψp b) Ψw=Ψm+Ψs−Ψp
c) Ψw=Ψm−Ψs+Ψp d) Ψw=Ψm−Ψs−Ψp
The correct relationship among different type of soil water is
a) Chresard = Echard + Hollard b) Hollard = Chresard + Echard
c) Echard = Hollard + Chresard d) Hollard = Chresard – Echard
In a fully turgid cell
a) TP=0 b) WP=0 c) DPD=0 d) OP=0
In which of the following plants, there will be no transpiration?
a) Aquatic, submerged plants b) Plants living in deserts
c) Aquatic plants with floating leaves d) Plants growing in hilly regions
The value of osmotic potential of an electrolyte is always
a) More than the electrolyte b) Less than the electrolyte
c) Same as the electrolyte d) None of these
Carrier protein, which allows the movement of molecules in opposite direction is
a) Antiport b) Symport c) Both (a) and (b) d) Uniport
In osmosis, there is movement of
a) Solute only b) Solvent only c) Both (A) and (B) d) Neither (A) nor (B)
If the osmotic pressure of cytoplasm in a cell is balanced by external solution, the solution must be
a) Hypotonic b) Hypertonic c) Atonic d) Isotonic
In thistle funnel experiment, what will occur if sugar solution is added to beaker, after the process
of osmosis stops?
a) The level of solution in thistle funnel rises up
b) The level of solution in thistle funnel lowers
c) The level of solution in beaker lowers
d) The level of solution remains unaffected in beaker

Page| 30

Water rises in the stem due to
a) Cohension and transpirational pull b) Turgor pressure
c) Osmotic pressure d) Root absorption
Term osmosis is specifically used to refer
a) Diffusion across the semipermeable membrane b) Diffusion across the permeable membrane
c) Secondary active transport d) Facilitated diffusion
Guttation is mainly due to
a) Root pressure b) Imbibition c) Osmosis d) Transpiration
Read the following statement carefully and choose the right answer from the codes given below
I. PMA and silicon oil of low viscosity are considered as antitranspirant
II. BAP, NAA and cobalt chloride is also used as antitranspirant
III. Abscisic acid affects the mechanism of opening and closing of stomata
IV. Starch of guard cells is converted into PEP ions by the process of hydrolysis
V. Potometer works on the principle of potential difference between the tip of the tube and that of plant
VI. Transpiration rate is directly proportional to the relative humidity
a) I, II, III, IV, V and VI b) I, II, III and IV are correct while V and IV are
incorrect
c) V and VI are correct, while, I, VI, III and IV are
incorrect
d) I, III, VI are correct, while II, IV, V are correct
When pea seeds and wheat grains are soaked in water, pea seeds showed more swelling than the
wheat. The reason is
a) Imbibitions capacity of proteins is more than that of starch
b) Presence of less hydrophilic colloids in the wheat grains
c) Cell membrane of pea seeds is more permeable
d) Cell wall of wheat grains are less permeable
The phytohormone, which increases the concentration of potassium in guard cells is also
responsible for the induction of
a) Apical dominance b) Triple response growth
c) Cell division d) Abscission
Choose the correct option in accordance to the statements given above
I. The positive hydrostatic pressure is also called as turgor pressure
II. Wall pressure is exerted to prevent any increase in protoplasm size
III. Osmosis is the movement of substances, which takes place along a diffusion gradient
IV. Plasmolysis is the result of reverse osmosis
a) I, II, III are correct IV is incorrect
b) II, I are correct, while IV and III are incorrect
c) III and IV are correct, while I and II are incorrect
d) Only II is correct
Water channels are possessed by a membrane to facilitate the movement of hydrophilic substances. These
channels are made up of
a) Eight similar type of aquaporin
b) Eight different type of aquaporin
c) Eight similar and eight different aquaporin
d) Do not possess any water channel
Who described mass flow hypothesis?
a) Munch b) Sir JC Bose
c) Kursanov d) Buchmann and Priestly
Water can be absorbed from a hypertonic external solution by

Page| 31

a) Withdrawing more water from the external
solution
b) Auxin treated cells
c) Adding a buffer in the external solution d) Cytokinin treated cells

In a fully turgid cell, …… is zero.
a) OP b) TP c) WP d) DPD
Why the transport of organic food through phloem is bidirectional?
a) Roots serve as source while leaves are the sink
region
b) Source and sink region are irreversible
c) The relationship between the two region (source
and sink) is variable and is dependent on season
and plant needs
d) Translocation of organic solute is regulated by
energy
Cohesion theory of water movement in plants was put forth by
a) Melvin cycle b) F F Blackman c) T W Engelmann d) Henry Dixon
Choose the correct statements regarding the uptake of mineral nutrients and food in plants
a) Even a little amount of exchange of material does
takes place between xylem and phloem
b) Most of the minerals enter the root through active
absorption
c) Due to variable relationship between source and
sink direction of sap flow in phloem is
bidirectional
d) All of the above
According to the transpiration-cohesion theory, the upward pull of water is transmitted to other water
molecules by cohesion, which is caused by
a) Hydrogen bond b) Hydrophilic cell walls c) Turgor pressure d) Osmosis
In plants, continuous water supply is due to
a) Osmosis b) Imbibition
c) Guttation d) Adhension-cohension forces

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NEET BIOLOGY

TRANSPORT IN PLANTS

: ANSWER KEY :
1) b 2) c 3) a 4) a
5) c 6) a 7) c 8) d
9) a 10) c 11) a 12) a
13) a 14) d 15) c 16) a
17) a 18) d 19) d 20) c
21) b 22) a 23) d 24) a
25) a 26) c 27) c 28) a
29) a 30) b 31) c 32) a
33) a 34) c 35) a 36) b
37) b 38) d 39) c 40) a
41) a 42) b 43) b 44) d
45) a 46) c 47) c 48) c
49) b 50) d 51) c 52) a
53) b 54) c 55) c 56) d
57) d 58) c 59) c 60) b
61) b 62) c 63) c 64) d
65) c 66) c 67) a 68) c
69) a 70) a 71) a 72) c
73) d 74) a 75) a 76) d
77) b 78) c 79) d 80) a
81) a 82) a 83) a 84) a
85) a 86) b 87) c 88) c
89) b 90) b 91) a 92) d
93) a 94) a 95) b 96) a
97) d 98) a 99) a 100) b
101) b 102) b 103) a 104) b
105) d 106) b 107) a 108) b
109) c 110) a 111) c 112) b
113) a 114) c 115) c 116) a
117) a 118) b 119) d 120) c
121) a 122) c 123) d 124) b
125) d 126) c 127) c 128) c
129) c 130) d 131) c 132) c
133) c 134) b 135) a 136) a
137) c 138) a 139) c 140) b
141) c 142) b 143) d 144) c
145) a 146) a 147) c 148) c
149) b 150) b 151) c 152) c
153) a 154) d 155) b 156) b
157) c 158) c 159) a 160) c
161) b 162) b 163) b 164) c
165) b 166) c 167) a 168) c
169) b 170) d 171) b 172) b
173) d 174) b 175) a 176) d
177) c 178) d 179) a 180) b
181) b 182) b 183) d 184) c
185) c 186) b 187) a 188) a
189) c 190) a 191) a 192) b
193) a 194) a 195) a 196) b
197) a 198) a 199) a 200) b
201) b 202) a 203) b 204) c
205) d 206) b 207) c 208) c
209) a 210) a 211) c 212) c
213) b 214) c 215) a 216) a
217) b 218) c 219) b 220) b
221) d 222) b 223) d 224) d
225) d 226) b 227) c 228) b
229) a 230) c 231) a 232) b
233) d 234) c 235) d 236) c
237) d 238) b 239) a 240) d
241) b 242) d 243) d 244) d
245) a 246) d 247) a 248) a
249) b 250) c 251) b 252) a
253) a 254) d 255) a 256) b
257) a 258) b 259) b 260) a
261) d 262) a 263) d 264) c
265) d 266) c 267) b 268) b
269) d 270) a 271) b 272) a
273) b 274) a 275) c 276) a
277) c 278) b 279) b 280) d
281) d 282) b 283) d 284) b
285) c 286) b 287) d 288) b
289) d 290) d 291) b 292) a
293) a 294) d 295) d 296) a
297) c 298) d 299) b 300) d
301) c 302) a 303) d 304) c
305) c 306) b 307) a 308) a
309) b 310) c 311) a 312) a
313) a 314) b 315) d 316) b
317) a 318) a 319) a 320) b

Page| 33

321) a 322) c 323) a 324) b
325) a 326) b 327) d 328) c
329) d 330) d 331) a 332) d

Page| 34

NEET BIOLOGY

TRANSPORT IN PLANTS

: HINTS AND SOLUTIONS :
1 (b)
The given diagram represents the transport of
two type of molecules by carrier proteins, which
is achieved with the activity of membrane proton
pump to solute exchange. ‘A’ depicts, uniport
method of transport-molecule move across the
membrane
‘B’ shows antiport method and symport method
(transport in same direction) is shown by ‘C’ in
the given diagram
2 (c)
Aquaporins are present in cell membranes. They
facilitate the transport of water soluble
substances through it. Aquaporins are also known
as channel proteins
3 (a)
Plasmolysis
4 (a)
Addition of solutes in a system or cell decreases
the energy of water. Pure water has the maximum
diffusion pressure. Water potential or chemical
potential of pure water is the difference in the
free energy per unit molal volume of water in a
system in reference to pure water at normal
temperature and pressure
5 (c)
The movement of sugars in the phloem begins at
the source, where sugars are loaded (actively
transported) into a sieve tube. Loading of the
phloem steps up a water potential gradient that
facilitates the mass movement in the phloem
6 (a)
The evaporative loss of water in the form of
vapours form the exposed part of plant is known
as transpiration. This evaporative loss of water
due to process of transpiration varies from plant,
i.e., around 2 L per day in sunflower, while it is
one tonne per day in elm tree. Rate of
transpiration is affected by relative humidity,
temperature, light, wind speed, atmospheric
pressure and availability of water
7 (c)
In herbaceous plants, when root pressure is
high and transpiration is low, plants may lose
this extra water in liquid drops from margins
of leaves. This process is called guttation. It is
very common during warm and humid nights.
These water drops contain salts, amino acids,
etc.
8 (d)
Water always moves from area of high water
potential to area of low water potential, i.e.,
from less negative to more negative. During
water absorption by root hair, the water
movement is possible if water potential of
vacuolar sap is lower than root hair.
9 (a)
The water remaining in dry soil and held as
very thin films around the soil particles is
called hygroscopic water.
10 (c)
Root pressure, a manifestation of active water
absorption is developed in xylem sap of roots of
same plants. It maintains optimum metabolic
activity and reduce transpiration and provide a
light push in overall process of water transport
because root pressure cannot transport water
upto the whole length of plant. Movement of
water is shown through xylem.
In symplastic movements, movement of water
occurs from cell to cell through their protoplasm,
which are connected by a bridge called
plasmodesmata
11 (a)
Transport of substances through membrane from
region of higher concentration to lower

Page| 35

concentration needs energy and transport is
called active transport
12 (a)
The value by which the diffusion pressure of a
solution is lower than that of pure solvent is
known as diffusion pressure deficit.
DPD or SP=OP-TP
At the equilibrium TP=WP
DPD=OP-WP.
13 (a)
The stomatal aperture is surrounded by guard
cells having chloroplasts
14 (d)
Mature stems of woody plants have a
peripheral water proof tissue called cork
(phellem). A number of scars known as
lenticels are found on the surface of cork.
Lenticels allow the gaseous exchange
between atmosphere and living cells below
the cork and also take parts in transpiration
(0.1 %).
15 (c)
In the light, the pH of guard cells becomes
increased due to consumption of CO2 in the
process of photosynthesis. Guard cells receive
K+ions from subsidiary cells. This decreases
the water potential of guard cells and leads to
migration of water from subsidiary cells to
guard cells.
Uptake of K+ ions is also balanced by Cl− ions.
16 (a)
Sorghum has high shoot root ratio (due to
more length) than maize. According to Parker
(1949), the ratio of transpiration is directly
proportional to shoot-root ratio.
17 (a)
If a plant cell is placed in a hypotonic
solution/pure water, water starts moving in
by endosmosis. As the volume of the
protoplast increases, it begins to exert
pressure against the cell wall (turgor
pressure). Normally, wall pressure is equal
and opposite to turgor pressure except when
cell becomes flaccid, So if cell’s turgidity
increases, wall pressure also increases.
18 (d)
Hormones, amino acids and sugars are
transported or translocated through phloem
19 (d)
Stocking has defined root pressure as a
pressure developed in the treachery elements
of xylem as a result of metabolic activities of
root. It is said to be a active process and
appears due to osmosis.
20 (c)
It is demonstration of transpiration by bell jar
experiment. It this experiment a potted plant is
placed on a slab and a dry bell jar is inverted over
it. Having sealed the edge of jar with wax or
Vaseline, the whole apparatus is left undisturbed.
After sometimes the inner surface of bell jar
became misty due to transpiration by plant
21 (b)
Xylem sap is composed of minerals and water and
is not driven by higher concentration of sugars,
while rapid flow of water does not affect the
conducting tissue and only the rate of
transpiration is increased
22 (a)
The most significant physiological feature of
stomata is their response to light. Generally
stomata open in the day time, i.e., light and
close at night or in darkness. These are called
as photoactive stomata. However, in succulent
plants like Kalanchoe of family- Crassulaceae,
the stomata open at night and close in the day
time. Such stomata are called scotoactive
stomata.
23 (d)
The direction of movement in phloem is
bidirectional and that of xylem is unidirectional.
Since the source-sink relationship is variable, the
direction of movement in the phloem can be
upwards or downwards, i.e., bidirectional. This
contrast with that of the xylem, where the
movement is always unidirectional, i.e., upwards
24 (a)
Pulsation theory for ascent of sap was
proposed by an eminent Indian scientist J C
Bose.
25 (a)
The water potential is the chemical potential
of water in a system or part of a system
expressed in units of pressure and chemical

Page| 36

potential of pure water at same atmospheric
pressure and temperature.
26 (c)
The solution whose osmotic concentration
(solute potential) is equal to that of another
solution is called isotonic solution.
27 (c)
Plants obtain most of their carbon and oxygen
from CO2 present in the atmosphere
28 (a)
When plant cell is kept in saline water,
exosmosis takes place, as a result of which
cell decreases in size.
29 (a)
When carrier proteins allow two type of
molecular movements together, it is termed as co
transport. It can be further divided into two types;
symport and antiport. In symport process, two
types of material are diffused in same direction
30 (b)
In 1980, Julius von Sachs, a German botanist,
demonstrated for the first time that plants
could be grown to maturity in a defined
nutrient solution in complete absence of soil.
This technique of growing plants in a nutrient
solution is known as hydroponics. These
methods require purified water and mineral
nutrient salts.
31 (c)
It is because of the close packing of water
molecules in the inter spaces and over the surface
of the imbibant particles
32 (a)
In rooted plants, transport of inorganic
substances like water and minerals occur by
xylem and it is unidirectional in case of water
33 (a)
Guttation is loss of water in liquid form from
uninjured part in plants. This water loss
occurs through hydathodes or water stomata.
Guttation usually occurs from tips and
margins of leaves during early morning when
there is high atmospheric humidity as during
wet reasons. Water stomata or hydathodes
are permanently opened pores.
34 (c)
Imbibition is a special type of diffusion when
water is absorbed by solids colloids causing
them to enormously increase in volume. The
classical examples of imbibitions are
absorption of water by seeds and dry wood.
35 (a)
A-Final level B-Dotpin
C-Initial level D-Sugar solution
E-Potato tuber
36 (b)
Transport of water and mineral in xylem is
unidirectional and sap move upwards due to
transpirational pull. While transport in phloem is
bidirectional and multidirectional, transport of
organic food by phloem takes place from the
source to sink
37 (b)
The rate of transpiration can be reduced by
using anti-transpirants. These can be used in
two ways

Metabolic inhibitors: PMA, ABA,
aspirin
Film forming antitranspirant: Silicon,
low viscosity, waxes.
BAP (Benzyl amino purine) is a cytokinin.
38 (d)
Statoliths are microscopic particles.
According to statolith theory given by
Haberlandt and Nemec (1900), the change in
position of statoliths under the influence of
gravitation causes differential growth.
39 (c)
In a plasmolysed cell, the space between
nucleus and plasma membrane is occupied by
isotonic solution.
40 (a)
Sugarcane (saccharum officinarum) is a
monocot plant of family-Poaceae. In gases
(Poaceae), the guard cells are dumb bell
shaped and their cell walls are thickened only
in the middle.
41 (a)
The water potential and osmotic potential of pure
water is zero
42 (b)
Proteins have a very high imbibing capacity,
starch less and cellulose least. This is why the

Page| 37

proteinaceous seeds, e.g., pea seeds will show
more imbibiton than those of wheat seeds.
43 (b)
Turgor pressure causes movements
44 (d)
Diffusion process takes place between
concentration of molecule solution and it is
process, where the movement of molecules occur
from a higher concentration to lower
concentration, either it is internal or external.
Higher the concentration gradient, higher will be
the rate of diffusion
45 (a)
In a ringing or Girding experiment, the ring of
bark, along with phloem is cut from the stem to
represent the path of organic nutrients by phloem
tissue. If phloem is not removed along with bark,
supply of organic food will be continue and plant
will survive. It xylem is girdled from main stem,
supply of minerals and salts is stopped in the
leaves and upper part of girdling site.
So, wilting of leaves takes place after sometimes.
In girdling experiment, root dies first as supply of
food is stopped. In flowering plant, sieve tube
transport food in the form of disaccaharides
(sucrose)
46 (c)
Generally, stomata are provided for water
loss but plants, which grow in xeric habitat
have sunken type of stomata in their lower
epidermis of leaves to minimize the loss of
water, e.g., Nerium.
47 (c)
Cohesion tension theory was proposed by Henry
Dixon and Jolly in 1894. It is greatly supported
and elaborated by Dixon (1914, 1924). It is also
called as transpiration pull theory and is based on
the following assumptions

Cohesive and adhesive properties of water
molecules
Continuous water column from root hairs
through stem to tip of leaves
Strong transpiration pull exerted by all the
transpiring leaves on the stem
48 (c)
The given diagram represents the process of
osmosis. i.e., the movement of water from its
higher concentration to lower concentration
through a semipermeable membrane
49 (b)
An account of 90% total transpiration occurs
through leaves, i.e., foliar. Remaining 10% takes
place through stem, flower and fruits etc. Cauline
transpiration is the loss of water from stem.
Ascent of sap in conducting tissues of plant is
affected by cohesion, adhesion and properties of
water
50 (d)
The food material synthesizes in leaves of
green plants and from seed during
germination is translocated to growing
regions and storage organs of plant.
51 (c)
Capillary water is the water present in
narrow spaces or microspores of the soil. It is
held in the soil by capillary force and
therefore, does not fall down to water level.
Capillary water is absorbed by plant roots.
52 (a)
ABA theory to explain the mechanism of
stomatal closure was proposed by Cowan et
al, in 1982. According to it formation of
abscisic acid (during drought or mid-day)
promotes reversal of H+⇌K+ pump and
increases availability of H+ inside the guard
cell cytoplasm and stomata close. Active K+
transport theory for opening and closing of a
stomata, was proposed by Imamura (1943)
and Fujino (1967). Proton (H+−K+)
transport theory was proposed by Levitt
(1974).
53 (b)
K+ions regulate the opening and closing of
stomata. Increased concentration K+ and
malate ions in the guard cells increases the OP
of guard cells, which results in decrease of
water potential. Due to which water enters
from adjoining subsidiary cells into guard cells
by endosmosis. Turgor pressure of guard cells
increases, which results in the opening of
stomata.
54 (c)
Mineral exists in soil as ions which are generally
absorbed from the soil by both active and passive
transport. Because sometimes concentration of
ions in soil is 100 times more as compared to

Page| 38

concentration in root system in its interior. So, all
mineral cannot be absorbed passively
55 (c)
Root hair zone (cell differentiation zone) in plants
is a specialised structure for water absorption. It
is the most efficient water absorption region in
roots. Inspite of water absorption, root hair zone
or root cells are incapable for photosynthesis
because of the absence of chlorophyll but use
oxygen for respiration
57 (d)
Adhesion is the attraction of unlike molecules
to each other, such as that between water and
the walls of xylem vessels in plants.
58 (c)
A trichome is initiated as a protuberance from
an epidermal cell. Generally, a dense covering
of woody trichomes controls the rate of
transpiration. They also reduce the heating
effect of sunlight. They aid in the protection of
plant body from outer injurious agencies.
59 (c)
The guard cells of stomata in land plants are
specialized epidermal cells which contain
chloroplasts. In rest of epidermal cells,
chloroplasts are absent. But chloroplasts of
guard cells are capable of poor
photosynthesis as there is absence of NADP
reductase enzyme.
60 (b)
The movement of water occurs from low DPD
cell to high DPD cell. DPD is equal but
opposite to water potential (algebraic sum of
solute or osmotic potential and pressure
potential).
Cell Water potential
(osmotic potential +
pressure potential
DPD
A -1+0.5=-0.5 +0.5
B -0.6+0.3=-0.3 +0.3
C -1.2+0.6=-0.6 +0.6
D -0.8+0.4=-0.4 +0.4
So, the correct sequence of the path of
movement of water is
B→D→A→C.
61 (b)
The experimental set up shown in the diagram is
simple potometer used for measuring the rate of
transpiration. In simple potometer, when water is
lost by the plant, it is taken from the glass tube
and as a
result, the mercury column rises
62 (c)
According to active K+ theory of Levitt, the
stomatal opening and closing is regulated by ATP
driven K+ exchange pump. According to this
theory, there is a accumulation of K+ in the guard
cells during day time 200. When guard cells have
more K+, endosmosis takes place, resulting in the
lowering of osmotic potential of guard cells. They
starts to absorb water from neighbouring cells
and becomes turgid to make a pore or opening in
the stoma.
Thus, stomatal opening takes place. Due to the
loss of K+ the osmotic concentration of guard cells
in comparison to adjoining epidermal cells
decreases. Therefore, exosmosis takes place and
guard cells becomes flaccid due to the loss of
turgidity. Thus, stomatal closure takes place
63 (c)
During the transport of water from the soil to
xylem, water moves through mainly two channels,
i.e., symplast and apoplast. Symplast when water
moves between adjacent cell through cytoplasmic
connection and when water moves through cell
wall, it is called apoplatic movement
64 (d)
Water potential is the difference in free energy or
chemical potential per unit molal volume of water
in a system in reference to pure water at normal
temperature and pressure and by increasing the
pressure its value also increases
65 (c)
The imbibants have negative water potential. As a
result when they come in contact with water, a
steep water potential is established between the
imbibant and imbibate
66 (c)
Phloem sap is composed of organic substances in
soluble forms. Sugar, hormone and water are the
constituent of phloem sap. If one analyse the
phloem sap chemically, presence of nitrogen and
mineral is expected in least amount. While in
xylem sap, its presence will be more
67 (a)
Mineral ions are frequently remobilised,
particularly from older, senescing parts. Older
dying leaves export much of their mineral content

Page| 39

to younger leaves. Similarly, before leaf fall in
decidous plants, minerals are removed to other
parts. Elements most readily mobilised are
phosphorus, sulphur, nitrogen and potassium.
Some elements that are structural components,
like calcium are not remobilised
68 (c)
Diffusion is process, which occurs in three forms
of matter, i.e., solid, liquid and gas. The process
occurs along the concentration gradient, i.e.,
movement of molecule takes place from higher
concentration area to lower concentration area
70 (a)
In plants, water and minerals both are
absorbed by the root hairs. Root hair zone is
also known as zone of maturation or
differentiation as the cells of this zone
undergo maturation and differentiation into
different types of primary tissues of the root.
71 (a)
DPD or Diffusion Pressure Deficit is an older term,
which was used for water potential. Due to the
pressure of DPD in a solution, it tends to make up
the reducion in diffusion pressure by absorbing
water. Therefore, DPD is also called as suction
pressure
72 (c)
Transport of water soluble substances (glucose,
sodium ions and chloride ions) is facilitated by
transport proteins. The transport proteins are
embedded in the lipid bilayer of cellular
membranes and provide sites at which such
molecules cross the membrane
The transport proteins themselves do not create a
concentration gradient. A concentration gradient
must already be present in order to facilitate
diffusion. A transport protein simply provides a
binding site that binds the specific molecule (𝑒.𝑔.,
glucose) or ion to be transported
After binding the specific molecule, the transport
protein changes its shape and carries the
molecule across the membrane where it releases
the molecule. The transport protein returns to its
original shape and waits to catch another
molecule to be transported
73 (d)
Process of diffusion is actively involved in various
processes of life like transpiration by plants,
respiration in livings and photosynthesis. It is a
part of all the three processes
74 (a)
Munch (1930) proposed the pressure flow
hypothesis which best explain the transport of
organic nutrients from the source (supply) to sink
(utilisation site). According to this theory, source
shows a high osmotic concentration than the sink.
When the organic substances from mesophyll
cells are (act as source) passed to the sieve tube
of phloem through their companion cell by active
transport, a high osmotic concentration is
developed in sieve tube and acts as a source.
Water is absorbed by sieve tubes from the
adjacent xylem and develop a high turgor
pressure. Thus, the transpiration of organic
nutrient takes place from a region of higher
turgor region to the area of lower turgor pressure
75 (a)
Each stoma (pl. stomata) remains surrounded
by two small, specialized, green, kidney
shaped epidermal cells called guard cells,
which are rapidly influenced by turgor
changes. Adjacent to each of the guard cells
are usually one to several other modified
epidermal cells called accessory or subsidiary
cells.
Sclerenchymatous cells are thick-walled
lignified, dead cells supportive in function.
These are not related with the structure of
stomata.
76 (d)
A-Stomal aperture, B-Guard cell, C-Cellulosic
microfibrils
77 (b)
Guttation is the loss or exertion of water in
the form of liquid droplets from the leaves
and other parts of an uninjured or intact
plant. Guttation takes place through special
structures called hydathodes. Water lost
during guttation contains inorganic and
organic components so, it is not pure.
78 (c)
Zone of cell differentiation or root hair zone is the
most efficient region of water absorption in
plants, which is made up of thousands of root
hairs. This zone is 1-6 cm in length. Root hairs are

Page| 40

specialised to absorb water and are 0.05-1.5 mm
in length and 10 um in breadth
79 (d)
The upper epidermises of monocots have
large, thin walled and empty bulliform cells or
motor cells containing water. These cells are
mainly concerned with rolling and unrolling
of leaf. The epidermis is cuticularized.
80 (a)
The movement of H2O occurs from high value of
Ψ𝑤 to low value of Ψ𝑤, i.e., from less negative
value to more negative value of Ψ𝑤
81 (a)
The rate of transpiration can be measured by
Farmer’s protometer or Ganong’s
photometer. These are based on the
assumption that the rate of transpiration is
nearly equal to the rate of absorption of
water. The opening and closing of stomata are
measured by porometer.
82 (a)
A cell swells up when kept in hypotonic
solution due to process of endosmosis.
83 (a)
Diffusion is rapid in gases then in liquid
diffusion of water through semipermeable
membrane is called osmosis.
84 (a)
When a plasmolysed cell is placed in
hypotonic solution, i.e., of lower osmotic
pressure, it regains its normal shape and size
due to DPD (Diffusion Pressure Deficit).
DPD=OP-TP
85 (a)
Due to wilting, the water potential becomes
equal to osmotic potential.
86 (b)
Sugar stored in roots may be mobilised to become
a source of food in the early spring as the source
and sink may be reversed depending on the
season
87 (c)
Pinus and orchid seeds cannot germinate and
develop into plants in the absence of mycorrhizal
association. In mycorrihzal association, the fungal
hyphae are specialised for absorption of water
and minerals by extending sufficient distance into
soil. The mycorrhizal association between fungus
and roots of plant are obligate. Absorption of
water along with mineral is an active absorption
and followed by osmosis. Fungus are
heterotrophic
88 (c)
Water potential is the difference in the free
energy or chemical potential per unit molal
volume of water in a system and that of water
at the same temperature and pressure. It is
represented by greek letter
Ψ (psi) or Ψw. The value of Ψw is measured
in bars, pascals or atmospheres, i.e., units of
pressure.
90 (b)
Due to continuous transpiration from the leaves
surface, mesophyll cells of leaves withdraw water
from deeper cells as its molecules are binded by
hydrogen bond. Deeper cells obtain water from
tracheary elements, which in turn cause a tension
in water column of tracheary elements.
As this tension is created by transpiration, it is
referred to as transpirational pull. On account of
this tension, the water column of plant is pulled
up passively below the top most part of plant. A
transpiration pull of 10-20 atm is sufficient to left
the water up to the height of tallest plant over 130
metre
91 (a)
Generally, stomata are associated with the water
loss from aerial parts of plants. But plants which
grow in xeric habitat have sunken stomata in their
lower epidermis of leaves to minimise the loss,
�
�.𝑔., Nerium
92 (d)
When a leaf peeling of Tradescantia is kept in
a medium having 10% NaCl solution, the cells
shrink in size, this is followed by separation
of protoplast from cell wall due to exosmosis.
This phenomenon is called plasmolysis.
93 (a)
Osmosis
94 (a)
The stomata presents in xerophytes, open at
night.
95 (b)
ABA (abscisic acid) causes stomata to close
by inhibibition of an ATP dependent pump in
the plasma membrane of guard cells. The

Page| 41

application of exogenous ABA on leaves of
normal plants causes closing of stomata
within a few minutes. ABA acts in the
presence of CO2, which decreases the pH of
guard cells. ABA includes the loss of K+ions,
which decreases the osmotic concentration of
guard cells as compared to adjacent
epidermal cells. This causes exosmosis and
turgidity of guard cell decreases.
96 (a)
The direction of translocation, i.e., transport of
organic substances and mineral nutrients is
multidirectional. However, it is unidirectional in
case of water and minerals
97 (d)
A mechanism involving electro-osmosis was
proposed independently by Fensom (1957)
and Jones (1958). According to this
hypothesis, the solute moves in positive
direction of electrical gradient along with K+
ions.
98 (a)
In both, facilitated diffusion and active transport,
there is an involvement of carrier transporter or
transporter proteins. These are highly specific
enzymes and shows sensitivity to inhibitors
99 (a)
Water potential is the difference in free
energy or chemical potential per unit molal
volume of water in a system and that of pure
water at the same temperature and pressure.
The water potential of pure water is zero and
it decreases on addition of solutes.
100 (b)
Long distance transport of organic and inorganic
substances in plants occur through complex
permanent tissues. Vascular tissues are also
permanent tissues, i.e., xylem and phloem
101 (b)
Xylem sap is water with dissolved ions.
Unidirectional upward movement of water and
mineral from the soil to the tip of leaves through
stem and branches of plants is called as ascent of
sap, which is carried out by tracheary elemental,
xylem
102 (b)
Passive absorption of minerals takes place as
mass flow, simple diffusion, facilitated
diffusion, ion exchange, Donnan equilibrium.
103 (a)
Pressure potential or positive hydrostatic
pressure or turgor pressure is the pressure, which
develops in the confined part of an osmotic
system due to the osmotic entry of water in it
105 (d)
Transport of minerals through xylem from the soil
to plant takes place by active transport. This
active transport need energy to move molecules
against the concentration gradient. This is
facilitated with membrane proteins due to less
concentration of minerals ions in the soil.
minerals are transported into root cells by active
transport
106 (b)
A-unidirectionally, B-casparian strips
107 (a)
In the majority of the plants, the shape of guard
cells in stomatal apparatus are kidney-shaped in
outline, which are joined at their ends. In the
members of Cyperaceae and Poacease, the shape
of guard cells is dump-bell shaped in outline.
Their middle portion are thick walled, while
expanded ends are thin walled
108 (b)
Transpiration pull.
If the stem of plant is cut under a state of tension
in xylem sap, the air will be pulled into the xylem
and the transport of water (xylem sap) remains in
continuity. However, it can be discontinued with
the introduction of air bubble in the xylem.
Copeland (1902) believed that air bubbles enter
into the xylem and break the tensile strength or
cohesion force between the water molecule
109 (c)
Munch proposed mass flow hypothesis. This is
also known as Munch hypothesis. According to
this, food material are translocated through
phloem along the concentration gradient from
the source to sink
110 (a)
The water potential (Ψω) is equal to osmotic
potential (ΨS)+ pressure potential (ΨP). Osmotic
potential is always in negative value. The water
potential is the chemical potential of water, which
is equivalant to DPD with negative sign.
Therefore, water potential (Ψ) of cell A is

Page| 42

ΨA=ΨS+ΨP=−18+8=−10
Water potential of cell B (ΨB) is
ΨB=ΨS+ΨP=−14+2=−12
Since, water moves from higher water potential to
lower potential, i.e., the flow of water will be from
cell A(−10 bars) to cell B (−12 bars)
111 (c)
Water molecules in apoplast pathway are unable
to penetrate the layer/bond of suberised matrix
called the casparian strip
112 (b)
Plant, which grows in xeric habitat have sunken
stomata in their lower epidermis of leaves to
minimise the loss of water like Nerium succulent
or drought avoiding plant store water (when
available in excess) in the form of mucilage, i.e.,
leaf succulent, while true xerophytes are not
succulent, like Calotropis
113 (a)
Apoplast pathway of water movement inside the
root provide the least resistance to movement of
water. However, the presence of lignin suberin
layer interrupts the water movement. This layer is
known as casparian strips
114 (c)
A characteristic of mass flow is that the
substances, whether in a solution or in a
suspension, are swept along at the same pair, as in
flowing river. Bulk flow can be achieved either
through a positive hydrostative pressure gradient
(𝑒.𝑔., a garden hose) or a negative hydrostatic
pressure gradient (𝑒.𝑔., suction through a straw)
115 (c)
The relationship between the source and sink is
variable and depends upon season or need of
plant. In early spring season, roots act as source,
while the buds of plant begin to behave like
utilisation site.
Similarly, during flowering and fruit ripening, the
flowers and fruits acts like sink region and their
source or supply of organic nutrient is completed
from the site or photosynthesis, which are green
young and older leaves of plants
116 (a)
Because of low atmospheric pressure which
permits more rapid diffusion of water. Such plants
develop xerophytic characters to avoid this
situation
117 (a)
After the ions have reached xylem through active
or passive uptake, or a combination of the two,
their further transport up to the stem to all parts
of the plant is through the transpiration stream
118 (b)
Process of water absorption and transpiration are
carried out continuously in plants. However,
around 98-99% of absorbed water by plant is
transpired through transpiration
119 (d)
Apoplast pathway of water movement inside the
root provide the least resistance to movement of
water. However, the presence of lignin suberin
layer interrupts the water movement. This layer is
known as casparian strips
120 (c)
The net force with which water is drawn into
a cell or root hair is equal to difference of OP
and TP and is known as diffusion pressure
deficit or suction pressure. DPD of pure water
is maximum (=1236 atm) and solvent moves
from cell of low DPD to high DPD.
DPD or SP=OP-TP
121 (a)
The water which is found freely in the pervious
rocks and deep in the soil is called groundwater. It
occurs above the impermeable stratum. Its upper
layer is known as water table
123 (d)
If the stem of plant is cut under a state of tension
in xylem sap, the air will be pulled into the xylem
and the transport of water (xylem sap) remains in
continuity. However, it can be discontinued with
the introduction of air bubble in the xylem.
Copeland (1902) believed that air bubbles enter
into the xylem and break the tensile strength or
cohesion force between the water molecule
124 (b)
The most accepted theory of ascent of sap is
transpiration pull theory or cohesion-tension
theory proposed by Dixon and Jolly. Loss of
water from mesophyll cells of leaf through
transpiration creates transpiration pull or
tension, which is transmitted downward and
is relieved when water is absorbed through
roots.
125 (d)
Diffusion is a slow process. It does not depend on
the living system and there is no need of energy. It

Page| 43

can take place in adjacent cells, adjacent tissues
and from one type of tissues to another. It is rapid
over short distances. However, it is extremely
slow over long distance transport
126 (c)
Loss of water from the aerial parts of plant
through continuous transpiration causes a suction
pressure or tension in the water column of plant.
This tension develops due to transpiration and is
also called as transpirational pull
127 (c)
Dry weight of plants can be calculated roughly by
reducing its water contents. The average dry
weight of herbaceous plants is 10-15% of its fresh
weight
128 (c)
The net force with which water is drawn into
cell or root hair is equal to difference of OP
and TP and known as diffusion pressure
deficit or suction pressure, i.e.,
SP or DPD=OP-TP.
129 (c)
When a cell is placed in hypertonic solution,
the protoplasm shrinks and leaves the cell
wall due to exosmosis and cell becomes failed.
The space between plasma membrane and
cell wall of plasmolyzed cell is occupied by
hypertonic solution.
130 (d)
Water is absorbed by germinating seeds
through the process of imbibitions and helps
in rupturing of seed coat. Imbibition is the
process of absorption of water by hydrophilic
surface of a substance without forming a
solution. It is a type of diffusion by which
movement of water takes place along a
diffusion gradient. During the process of
imbibitions, volume of imbibant is changed,
heat is produced and imbibitional pressure is
developed.
131 (c)
Water potentials of the given cells are
Ψ=Ψs+Ψp
A=-0.87+0.44=-0.43
B=-0.92+0.34=-0.58
C=-0.68+0.27=-0.41
As water moves from greater water potential
to less, root hair, root cortical and leaf
mesophyll cells are C, A, B respectively.
132 (c)
Transpiration pull and cohesion-tension
theory was proposed by Dixon and Jolly
(1894). The molecules form a continuous
column by cohesion. The cell walls of xylem
vessels have a strong affinity for water
molecules, i.e., adhesion. Loss of water from
aerial parts through transpiration causes a
suction pressure in the water column of plant,
which is called transpiration pull.
133 (c)
A-Phloem, B-Sugars enters the sieve tube, C
Sugars leaves the sieve tube
134 (b)
Being a positive force, turgor, pressure opposes
the entry of water if large amount of water enters
in a plant cell
135 (a)
Suction pressure or transpiration pull is a tension
caused by transpiration from the surface of leaves
in a plant. This tension or pull creates a tension in
the water column of xylem, which in turn absorbs
water from the soil along with minerals.
Absorption of ions or minerals is affected by
transpirational pull. Pressure flow hypothesis or
Munch flow hypothesis depends completely on
the existence of mechanism for loading organic
nutrients (sugars) into sieve tube phloem and
deliver the same to the site of utilisation. Source
sink relationship is variable
136 (a)
Opening of stomata does not affected by
�
�𝟐(nitrogen). N2 is present in free state in
atmosphere/air, which is used in nitrogen
fixation by some important bacteria but does
not affect the opening and closing of stomata.
137 (c)
Osmosis is flow of solvent from lower
concentration to higher concentration of
solution through a semi-permeable
membrane.
138 (a)
Cohesion force is one of the force responsible for
water transport in xylem tissue. It is the force
between water molecule. Water molecules remain

Page| 44

joined to each other due to cohesion force. Water
column present in the tracheary element of xylem
can bear a tension or pull of up to 100 atm only
due to cohesion force. So, this is also known as
tensile strength
139 (c)
Osmosis is the diffusion of water molecules
through a differentially permeable
membrane. Endosmosis leads to diffusion of
water into the cell and thus, cell becomes
turgid.
141 (c)
In apoplast pathway, water passes from root
hair to xylem through the walls of intervening
cells without crossing any membrane or
cytoplasm.
Water potential of pure water at atmospheric
pressure is 0 Mpa, addition of solutes reduce
water potential (to a negative value).
In symplast pathway, water passes from cell
to cell through their protoplasm. It does not
enter cell vacuoles. The cytoplasms of the
adjacent cells are connected through bridges
called plasmodesmata.
Membrane permeability is the ability of a
membrane to allow passage of gases, liquids,
solutes (dissolved substance) through it. It is
depend upon two factors- nature of
membrane (membrane composition) and
nature of passing substance.
142 (b)
The pressure exerted by the protoplasm
against the cell wall is called turgor pressure.
Turgor pressure maintains the shape of a cell.
143 (d)
Transporter proteins are integral part of both
facilitated and active type of transport method.
Carrier proteins found in facilitated diffusion and
active transport are different and specific.
Generally, facilitated diffusion is not an energy
involvement process.
While active transport needs energy. Transporate
of substances in active process reaches to
maximum level (saturation point) when all the
proteins are being used completely
144 (c)
Root hair absorbs water from soil through
osmosis.
145 (a)
Mineral matter in the soil are responsible for
holding the water present in the soil. They are of
following 5 types according to their size in
ascending order clay, slit, fine sand, coarse sand
and gravel. Clay having mineral salt, is more
active chemically and shows higher capacity to
retain water and ions. A loam soil is made up of
ratio 1:2:2 of clay, slit and sand respectively.
While sandy soil has little clay matter and shows
least retaining capacity and is not fit for plant
growth
146 (a)
Phloem sap is mainly water and sucrose
147 (c)
Passive absorption of water by the root
system is the result of tension on the cell sap
due to transpiration.
148 (c)
If the medium is more dense, the molecules,
atoms, icons of solids, liquid or gases will take
more time to get evenly distributed but
equilibrium will positively be reached due to
kinetic energy of diffusing particles.
149 (b)
Dilute NaCl solution acts as hypotonic
solution. So, when flowers are cut dipped in
dilute NaCl solution, endosmosis occurs and
the cells of flowers swell.
150 (b)
Munch hypothesis is based on translocation of
food due to turgor pressure (TP) gradient.
151 (c)
Water potential in a cell is equal to algebraic
sum of solute potential and pressure
potential.

Cell Water Potential DPD
A -0.21+0.05=-0.16 +0.16
B -0.22+0.02=-0.20 +0.20
C -0.23+0.05=-0.18 +0.18
Water potential is equal but opposite to DPD.
Water move from low DPD cell to high DPD
cell.
152 (c)

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Water rises beyond the point at which it
would be supported by air pressure because
evaporation from the plant leaves
(transpiration) produces a force that pulls
upward on the entire column of water. The
forces of adhesion and cohesion maintain an
unbroken column of water. Thus,
transpiration facilitates absorption of water
by roots.
153 (a)
Carrier molecules or carrier proteins involved in
facilitated diffusion, facilitate the diffusion of
hydrophilic substances through biological
membrane. They are specific and allow the cells to
select solute of an appropriate size to be
transported. Carrier proteins can increase the
rate of diffusion and may undergo change upon
binding to solutes
154 (d)
Phenyl mercuric acetate is used as an
antitranspirant.
155 (b)
Statement I, II and IV are correct III is incorrect
156 (b)
According to Munch flow model or pressure flow
hypothesis, the correct sequence of transport of
organic nutrients from source to sink is that first
of all food material synthesis takes place then it is
transported from cell to cell in the leaves from
leaves cell (mesophyll cell). It is passed into the
sieve tube through their companion cells by an
active transport
Now sieve tube shows high osmotic concentration
and absorb water from the adjacent xylem.
Having absorbed water, they became turgid and
organic nutrients are transported from a region of
higher turgor pressure to a region of lower turgor
pressure
157 (c)
Transpiration is the loss of water from the aerial
part of a living plant. Transpiration may be
stomatal (90%), cuticular (3-9%) and lenticular
(0.1%). Transpiration is absent in submerged,
hydrophytes due to the absence of stomata in the
leaves of submerged plant, i.e., potamogeton
158 (c)
Stomata are minute pore complexes found
mainly in the epidermis of leaves. Each stoma
is surrounded by two small but specialized
green epidermal cells called guard cells. Their
walls are differentially thickend and elastic.
They control opening and closing of stomata.
159 (a)
Wilting occurs, when rate of transpiration is
higher than absorption, which leads to excess
loss of water than absorption. Transpiration
is a physical process, in which the water
evaporates in the form of vapours from aerial
parts of plants. It may be stomatal, cuticular
or lenticular.
160 (c)
Positive force-turgor pressure (hydrostatic
pressure) or pressure potential (Ψp) is kept
under check by wall pressure. In a plasmolysed
cell, turgor pressure is nill therefore, osmotic
pressure (Ψs) becomes equal to DPD (Ψw)
161 (b)
Water present due to surface tension in
minute capillaries or pore formed by soil
particles is called capillary water. It is the only
form of soil water which is absorbed by the
roots of plants, i.e., available water.
162 (b)
Proteins have a very high imbibing capacity,
starch less and cellulose least. This is why, the
proteinaceous seeds, 𝑒.𝑔., pea seeds will show
more imbibition than those of wheat seeds
163 (b)
The magnitude of root pressure ranges
between 1-5 atm.
164 (c)
Cell membranes possess certain pores, which are
called porin. These are present in the outer
membrane of mitochondria, plastids and in some
bacteria. These large proteins pores provide
passage for small sized proteins. They are also
called transport proteins, which can be divided
into two types; carrier proteins and channel
proteins. Carrier proteins bind to the particular
substances, while channel proteins allow
movement of an appropriate sized solute to be
transported and this in turn is delivered to the
outer side of the membrane by carrier proteins
165 (b)
When RBC and a plant cell are placed in
distilled water, endosmosis takes place as a
result of which RBC would increase in size

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and burst, while the plant cell would remain
about the same size because of the presence
of rigid cell wall.
166 (c)
Halophytes or plants in saline soil shows
maximum osmotic pressure, 𝑒.𝑔., Atriplex
confertifolia has an OP of 202.42 atm. Mesophytes
have an osmotic pressure of 5-15 atm, whereas
10-30 atm is exhibited by xerophytes
167 (a)
The strinkage of the protoplast of a living cell
from its cell wall due to exosmosis under the
influence of a hypertonic solution is called
Plasmolysis. When a cell is plasmolysed, it
becomes flaccid. In a flaccid cell, turgor
pressure (TP) becomes zero and DPO become
equal to OP as DPO= OP- TP.
168 (c)
Hydathodes or water pores, unlike stomata,
are always open as their guard cells are
immobile.
169 (b)
The water potential (Ψ) is equal to osmotic
potential (Ψs) + pressure potential (Ψp).
Osmotic potential is always in negative value.
The water potential is the chemical potential
of water, which is equivalent to DPD with
negative sign.
Therefore, water potential (ΨA) of cell-A is
ΨA=Ψs+Ψp=-18+8=-10
Water potential of cell-B(ψB) is
ΨB=Ψs+Ψp=-14+2=-12
Since, water moves from higher water
potential, the flow of water will be from cell-A
(-10 bars) to cell-B (-12 bars).
170 (d)
Transpiration can be categorised on the basis of
plant surface and are of following types, stomatal
transpiration, cuticular transpiration, lenticular
transpiration and bark transpiration.
Out of them, stomatal transpiration depend upon
the stomata of leaves and continue till the stomata
remains open. While transpiration from cuticle,
lenticels and bark continues throughout day and
night
171 (b)
Imbibition is a special type of diffusion when
water is absorbed by solids-colloids causing them
to enormously increase in volume. The classical
example of imbibition are absorption of water by
seeds and dry wood
172 (b)
Limiting plasmolysis is the first stage of
plasmolysis, during which the pressure on the
wall is reduced and the wall contracts causing the
reduction in cell wall simultaneously. During the
second stage, the protoplast withdraws itself from
the corners. This stage is known as incipient
plasmolysis. Due to continued exosmosis,
protoplasts shrink further and withdraws from
the cell wall except on or few points. This is the
last stage and is called evident plasmolysis
173 (d)
Water-a vital component of life that occupy about
72% of the earth surface. There are about 85-90%
of fresh weight of the plant tissue comprised of
water. Water melon contains around 92% of
water of its fresh weight
174 (b)
Selectively permeable membrane, viz,
membrane of root hair and tonoplast
(membrane of vacuole) allows passage of
certain substance more readily than others.
175 (a)
Symplast is a connection between two cells, which
involves, cytoplasm cell membrane and
plasmodesmate and not have cell wall in direct
contact
176 (d)
Movement of hydrophilic moiety substance is
facilitated by aquaporin and ion channels, which
is the constituent of cell membranes. They plays a
role in passive transport of water soluble
substances and do not set up a concentration
gradient. Hence, diffusion of hydrolphilic
substances along the concentration gradient
through transporter carrier protein, with no
energy involvement is termed as facilitated
diffusion
177 (c)
Imbibition.
Imbibition is a special type of diffusion when
water is absorbed by solids-colloids causing them
to enormously increase in volume. The classical
example of imbibition are absorption of water by
seeds and dry wood

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178 (d)
Water potential is the difference between free
energy of water molecules in pure form and
energy of water in the solution. Water
potential depends on solute concentration,
atmospheric pressure.
179 (a)
Succulents or drought avoiding plants sore
water (when available in excess) in the form
of mucilage, leaf succulent. True xerophytes
are non-succulent like Calotropis.
180 (b)
Transport of organic nutrients from source to sink
can be summarised as the osmotic movement of
water into sugar loaded sieve tube from adjacent
xylem. This creates a higher hydrostatic pressure
or turgor pressure in the sieve tube (source) than
the sink. Organic nutrients are transported from
the region of higher turgor pressure to the region
of lower turgor pressure.
Organic nutrient are transported along the
concentration gradient and pressure gradient.
Sieve tubes and sieve cells of phloem are the
channels of transport in flowering plant and non
flowering plant, respectively
181 (b)
The path of water movement from soil to
xylem is
soil→root
hair→cortex→endodrmis→pericycle→protoxy
lem→metaxylem
182 (b)
Stomata of CAM plants are closed during most
of the day time and open during night (i.e.,
scotoactive) because these plants survive in
dry and hot environmental conditions. These
plants have the capacity to store CO2during
night and this CO2 is used in photosynthesis
during day time when stomata are closed.
183 (d)
Proton (H+−K+) transport theory was proposed
by Levitt (1974). According to this theory, there is
a accumulation of K+ ions in the guard cells
during day time which in turn causes endosmosis,
due to a decrease in water potential of guard cell.
Guard cells thus, become turgid and stomatal
opening takes place
184 (c)
H+−K+exchange pump for stomatal
movement was given by Levitt (1974).
According to this, there is accumulation of K+
ions in the guard cells during day time. A rise
in pH during day time causes hydrolysis of
starch to form organic acid, i.e., phosphoenol
pyruvate (PEP).
185 (c)
Surface tension does not help in molecular
transport. The process of diffusion and
osmosis, transport molecules without using
energy but in case of active transport, energy
(ATP) in utilized.
186 (b)
Ascent of sap is passive and occurs along the
concentration gradient. Hence, there is no need of
energy in the process
187 (a)
In roots, endodermis is the innermost layer of
cortex. Some of the enddermal cells present
opposite to the xylem patches are thin-walled
and are called passage cells or transfusion
cells. Passage cells help in transfer of water
and dissolved salts from cortex directly into
the xylem and ultimately to the pericycle.
188 (a)
Active water absorption involves symplast
movement of water through living protoplasm,
vacuole and plasmodesmata of cells. Passive
water absorption involves apoplast (movement of
water through inter cellular spaces and cell wall
of cells)
189 (c)
Concentration gradient must already be present
for molecules to diffuse even if facilitated by
proteins. Transport rate in facilities diffusion
reaches a maximum when all of the protein
transporters are being used (saturation)
190 (a)
Osmotic pressure of a solution is greater than
pure solvent.
191 (a)
Measurement of transpiration can be done
with the help of potometer. It works on the
principle that amount of water absorbed
equals the amount of water transpired.
192 (b)

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The pathway of water movement inside a root is
of two types; apoplast pathway and symplast
pathway. In symplastic movement, the flow of
water occurs from cell to cell through their
protoplasm. In this pathway, the adjacent cells are
connected through plasmodesmata.
In this system, water has to pass through
plasmalemma least at one place. Symplastic
moment may be aided by cytoplasmic streaming
193 (a)
Transport of minerals through xylem from soil
takes place by active transport because the ions
are transported against concentration gradient.
So, there is a requirement of energy which is
provided by ATP
194 (a)
Opening and closing of stomata is controlled and
regulated by guard cells of stomata. Each stoma is
surrounded by two small specialised green
epidermal cells. These two cells are called as
guard cells. Their walls are differentially
thickened and elastic. The shape of guard cells are
kidney shaped and dump-bell shaped in dicot and
monocot, respectively
195 (a)
Stomata are also called stomates.
196 (b)
The diffusion of hydrophilic substances along the
concentration gradient through fixed membrane
transport protein without involving energy
expenditure, is called facilitated diffusion
197 (a)
In Girdling or ringing experiment, the path of
organic nutrients in the stem of plant is
represented, which is carried out by phloem. In
the experiment, a ring of bark along with phloem
is cut from the stem. Due to the absence of phloem
in the ringing part, translocation of food does not
takes place and the same is accumulated above
the ring. Bark also swells up and may give rise to
adventitious roots
198 (a)
Guttation takes place through special
structures called hydathodes. There are also
called water stomata.
199 (a)
A decrease in solute concentration in guard
cells will cause decrease in solute potential
and thus, an increase in the water potential.
200 (b)
Water movement between the two system takes
place from the system having higher water
potential or more energy to the system containing
lower water potential or low energy. So, during
water absorption from the soil, the water
potential of the root cells is lower than that of the
soil
201 (b)
Water potential is a concept fundamental to
understanding water movement. Solute potential
and pressure potential are two main components
that determine water potential
202 (a)
The rate of transpiration is inversely
proportional to the relative humidity, i.e., the
rate of transpiration is lower when relative
humidity is higher.
203 (b)
Guard cells help in transpiration. Each
stomatal opening is surrounded by two
specialized epidermal cells, called guard cells.
Because of their small size guard cells are
rapidly influenced by turgor change and thus,
regulate the opening and closing of stomata.
204 (c)
In plants, water and minerals both are absorbed
by root hairs of root hair zone. The root hair zone
is also known as zone of differentiation or
maturation. The cells of this zone undergo
maturation and differentiation into different
types of primary tissue of the roots
205 (d)
A mechanism involving electro-osmosis was
proposed independently by Fensom (1957)
and Jones (1958).
206 (b)
Mycorrhiza is a mutual association between
fungus and roots of gymnosperms, like Pinus. In
this relationship the fungal hyphae extends into
the soil and absorb water and minerals from the
soil. This absorbed minerals and water is handed
over to the roots of the plants, which in turn
provides sugar and N-compound to the fungal
hyphae
207 (c)
Facilitated diffusion and active transport are two
important processes of movement of substances,
into and out of the cells. These two processes are

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selective and specific i.e., cells are allowed to
select the uptake substances (facilitated
diffusion) while active transport is highly specific
due to the expenditure of energy
208 (c)
A dry alive seed contains around 10-15% water of
its weight. Water is a major component of life
which is generally absorbed by plants in variable
quantity according to their metabolic
requirement. A mature maize plant absorb about
3 L water/day, while a mustard plant can absorb
the water equal to its weight in only 5 hrs. Hence,
water is considered the limiting factor for plant
life, growth and development
209 (a)
Guttation refers to the exudation of water
droplet (in the form of salt solution) from the
margins and tips of leaves. Guttation water is
exuded from the group of leaf cells through
specialized openings or pores called
hydathodes. It occurs in some angiosperms
like garden nasturtium (Tropaeolum)
Colocasia, tomato, etc, and is most noticeable
where transpiration is suppressed and
relative humidity is high such as during the
night. It also takes place early in the morning
when soil moisture, root pressure and rate of
water absorption are higher.
210 (a)
Endodermis
211 (c)
The net direction and rate of osmosis depends on
both the pressure gradient and concentration
gradient
212 (c)
Surface tension does not help in the molecule
transport.
213 (b)
Water is a major component of all living cells.
Movement of molecule takes place through cell
membranes. Lipid soluble molecules can easily
pass through the cell membranes, while
hydrophilic substance face difficulty to pass
through these membranes
214 (c)
Absorption of water is increased when
concentration of soil solutes is low, when the
soil has low concentration of solutes the
water concentration must be more so
absorption of water by the cell will b more at
relatively high content of water. Because
water, moves from higher concentration to
lower concentration, i.e., diffusion takes place.
215 (a)
When a cell is placed in hypertonic solution, the
protoplasm shrinks and leaves the cell wall due to
exosmosis and cell becomes flaccid. The space
between the plasma membrane and cell wall of
plasmolysed cell is occupied by hypertonic water
216 (a)
According to the active K+ theory of Levitt, there
is influx of K+ in the guard cell from epidermal
cells, which are balanced by Cl−. At present, the
role of K+ in stomatal opening in universally
accepted. In CAM plants, stomata remains closed
during day time 𝑒.𝑔., Opuntia, pineapple etc.
Casparian strips present in the walls of
endodermal cells control the amount of water and
solute, which is absorbed, by the plants, CAM
plants have capacity to store CO2 during night and
the same is used in photosynthesis during day
time when stomata are closed
217 (b)
Active transport uses specific transporter
proteins called pumps, which use metabolic
energy (ATP) to move ions or molecules
against the concentration gradient.
218 (c)
A-control points, B-quantity, C-type, D-xylem
219 (b)
Levitt (1974) proposed ATP-driven H+−K+
exchange pump mechanism in guard cells for
the stomatal opening and closing. According
to it, there is accumulation of K+ ions in the
guard cells during day time. When guard cells
possess more K+, endosmosis takes place
lowering the osmotic potential of guard cells,
they become turgid and stomatal opening
takes place.
220 (b)
Diffusion is an important process of transport. It
is also related to gaseous exchange in plants.
Facilitated diffusion is comparatively a slow
process than active transport and transport of
molecule occurs along the concentration gradient
in diffusion

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221 (d)
Cohesion adhesion theory for water movement
(ascent of sap) in plants water proposed by Dixon
and Jolly in 1894 and again elaborated by Dixon
(1914, 1924). Now-a-days, this theory for ascent
of sap is regarded as most applicable and
acceptable in plants transport
222 (b)
Seed coats are made up of cellulose. And the
cellulose has comparatively little imbibitional
capacity, so little water is absorbed and seed coats
break. The most important of the plant imbibants
are protein, pectic compounds, starch and
cellulose, which can imbibe large amount of
water. Some of the proteins can imbibe up to 15
times their own volume
223 (d)
The chief sinks for the mineral elements are the
growing regions of the plant, such as the apical
and lateral meristems, young leaves, developing
flowers, fruits and seeds, and the storage organs.
Unloading of mineral ions occur at the fine vein
endings through diffusion and active uptake by
these cells
224 (d)
To prevent loss of water, tropical deciduous
forest trees shed their leaves.
225 (d)
In diffusion process, the rate of diffusion of
substances depend upon the concentration
gradient, permeability of the membrane,
temperature and pressure
226 (b)
A newly detached twig from a plant exudate a
fluid of organic food of plant like sugar from the
detached part/cut part. The fluid is known as
phloem sap. Vascular tissue phloem transports
organic food in plant parts from the origin site or
source
228 (b)
Active transport is the movement of a
substance from a region of lower
concentration to region of higher
concentration i.e., against the concentration
gradient. This process involves the movement
of free-energy gradient, they require the
expenditure of energy from the breakdown of
ATP and are, therefore, sensitive to factors
affecting metabolism.
229 (a)
Diffusion is process in which uncharged
molecules pass easily through a biological
membrane. However, water soluble substance
face difficulty to cross the membrane and the
transport of these hydrophilic molecules are
facilitated by carrier proteins, which are
possessed by cell membrane. The overall process
do not require energy and is referred to as
facilitated diffusion
230 (c)
Very few plants are able to send their roots upto
the fringe of water table because of the absence of
air. However, phreatophytes are those plant,
which can send and absorb the water from water
table, 𝑒.𝑔., populus deltoides, tamarik, etc.
231 (a)
Transport of substances over longer distances
through vascular tissue is termed as translocation
and this translocation of different substances
either inorganic minerals or organic substances
(like sugar) occurs through a mass or bulk flow
system.
This mass flow of substance is unidirectional in
case of water, while it is multidirectional in case
of organic solute and minerals
232 (b)
The products of photosynthesis are generally
transported by phloem to the various parts of
plants. This transport of organic solutes like sugar
(sucrose) along with water occurs bidirectionally
and multidirectionally
233 (d)
In facilitated diffusion, the rate of diffusion is
affected by the solubility of molecules in lipids,
concentration gradients, molecular size of the
molecules, etc. Availability of carrier molecules
also affects the rate of diffusion in facilitated
transport
234 (c)
Term DPD (Diffusion Pressure Deficit) was coined
by Meyer
235 (d)
Transpiration, tension, cohesion and adhesion are
those factors, which plays an important role in
upward movement of xylem sap in plants.
Transpiration exerts transpiration pull. Due to
cohesion force, water molecules in water column
are joined to each other. Adhesion force between
the walls of tracheary element and water

Page| 51

molecule produce surface tension, which accounts
for high capillarity through tracheary elements.
While plasmodesmata are bridge-like structures,
which join adjacent cells in symplastic movement
of water
236 (c)
The rate of diffusion of a substance along the
concentration gradient does not increase
continuously. While the concentration difference
of the molecules across the membrane increases
when the process is of carrier type.
This happens because after a certain level, the
carrier protein gets saturated
237 (d)
According to pressure flow hypothesis, sieve tube
system show better adaptation for mass flow of
organic nutrients. Due to the process of
photosynthesis, source region is always rich in
osmotic concentration. So, they pass organic
nutrient into sieve tube by active process which in
turn produce high osmotic concentration in sieve
tube.
Sieve tube absorbs water from adjacent xylem
and develop a gradient of turgor pressure. Now,
the organic nutrients are transported from an
area of higher turgor pressure to the region of
lower turgor pressure (sink or utilisation site)
238 (b)
It is due to choking of roots by water logging. It is
called flopping
239 (a)
Graham’s law of diffusion can be represented
by the following formula
Rate of diffusion ∝ 1
√Density of particle

240 (d)
Cohesion theory or transpiration pull theory
for the ascent of sap in plants, was given by
Dixon and Jolly (1894).
241 (b)
Sodium, which is essential for animals is not
required by most of the plants.
Water potential is the difference between the
free energy of water in a system and free
energy of pure water at atmospheric
pressure. The water potential of root cells is
lower than the water potential of soil.
Cohesion-tension or transpiration pull theory
is the most accepted theory of water
movement in plants.
242 (d)
Apoplast pathway consists of interconnecting cell
wall, intercellular spaces, cell wall of endodermis
excluding the casparian strips, xylem and
tracheary elements. This system is considered
non-living and is continuous throughout the plant.
Symplast pathway consists of the living parts of
the plant and is made up of interconnected
protoplast adjacent cells
243 (d)
Ψ𝑤
244 (d)
Water potential is the difference in the free
energy or chemical potential per unit molal
volume of water in a system and that of pure
water at the same temperature and pressure.
It is represented by greek letter Ψ (psi) or
more accurately Ψw
Water potential or Ψw is the sum total of
Ψs and Ψp.
Ψw=Ψs+Ψp
Where, Ψs→ solute potential
Ψp→ pressure potential
245 (a)
In water conducting tissues, tertiary wall is
represented by swollen nodules.
246 (d)
Translocation of organic nutrients by phloem can
be explained accurately by pressure flow model of
Munch. According to the model, the source region
always shows higher osmotic concentration. Sieve
tube with loaded organic food absorb water from
nearby xylem and develop a higher turgor
pressure. Movement of organic food occur from
an area of higher turgor pressure to a region of
lower turgor pressure
247 (a)
A little amount approximately around 0.2% of
absorbed water by plant is used in process of
photosynthesis
248 (a)
Transpiration pull and cohesion-tension
theory of ascent of sap was proposed by
Dixon and Jolly (1894). The molecules of
water show cohesion and molecule of water

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and vessel wall show adhesion. Due to these
forces water column does not break and
pulled upward by the force called
transpiration pull. The transpiration pull is
developed due to transpiration.
250 (c)
Field capacity is generally defined as ‘the
water content of an undisturbed soil’ after it
is saturated by rainfall and drainage of
gravitational water has completely stopped.
251 (b)
Active transport is a fast process comparative to
passive transport and it occurs against the
concentration gradient, i.e., material substances
are transported from a region of lower
concentration to higher concentration. While in
diffusion, transport of substances occur along the
concentration gradient
252 (a)
In mycorrhizal association, a large number of
fungal hyphae are associated with the roots of
higher plants in which hyphae extend to sufficient
distance into soil and have a large surface area.
These hyphae absorb water and mineral from the
soil and pass them to roots. Roots provide sugar
and nitrogen compound to the fungal hyphae
253 (a)
Active transport of solute occurs against the
concentration gradient of potential gradient, i.e.,
movement of solute takes place from a lower
chemical concentration to higher chemical
concentration. That is why, it is also considered as
uphill transport
254 (d)
Transport processes, facilitated diffusion and
active transport are selective and specific because
cells are allowed to select substances for uptake.
Facilitated diffusion does not support uphill
transport of substances, does not support uphill
transport of substances, does not require ATP
energy and movement of transport proteins are
present
255 (a)
Ascent of Sap in plants was demonstrated by
Girdling experiement. In this experiment, the
cortex and phloem of a plant are removed.
Due to which, conduction of food towards the
cortex is stopped and conduction of water
towards the stem by xylem remain unaffected
i.e., ascent of sap occurs. For sometime, plant
may survive, but after a period it dies due to
the absence of sugar in root cells.
256 (b)
The value of water potential is always negative or
less than zero. Water potential of a solution is
determined by using pure water as the standard
of reference, which has zero water potential at
normal temperature and pressure.
The presence of solute particles reduce free
energy of the water. Hence, it decreases the water
potential in negative value. So, water potential of
a solution is always less than zero
257 (a)
Loss of water in liquid phase from the margin and
tips of leaves in many herbaceous plant is
referred to as guttation. Bergerstein first studied
the phenomenon of guttation in 1887. Guttation is
not observed in all plants, it is observed in cereals
like wheat, maize, oat, etc.
258 (b)
Hollard is the amount of total water present
in soil. Chresard is the amount of water,
which cannot absorbed by the plants.
Thus, Hollard=Chresard+Echard
Or Chresard=Hollard-Echard
259 (b)
The cell will decrease in size due to
exosmosis.
260 (a)
The loss of water from the living tissue of
aerial parts of plant in the form of water
vapour is called transpiration. More than 95%
of total loss of water takes place through
stomata. Opening and closing of stomata
occurs due to turgor change in guard cells.
261 (d)
The water moves from lower DPD to higher
DPD.
262 (a)
Plasmolysis is the phenomenon of shrinkage
of protoplasm from the cell wall due to
exosmosis of under the influence of some
hypertonic solution (i.e., a solution of lower
water potential than the cell’s water
potential).
263 (d)

Page| 53

The stomatal movement is affected by many
factors like light, temperature, CO2
concentration, water deficit, turgor pressure,
growth hormone, atmospheric humidity, etc.
264 (c)
The water potential (Ψw) in a plant cell or
tissues is equal to the algebraic sum of solute
potential (Ψs) due to dissolved solutes and
the pressure potential (Ψp) due to pressure
developed within the cells or issues, i.e., Ψw=
Ψs+Ψp.
265 (d)
According to mass-flow hypothesis, there is a
mass flow of mineral ions into the root along
with transpiration current. Actually,
transpiration creates a suction pressure or
transpiration pull, conveyed from leaf xylem
to root hair, which causes absorption of water
from the soil passively. A large amount of ions
are also absorbed along with the absorption
of water. When the rate of transpiration is
high, absorption of water increases due to
increased suction pressure and along with
water, absorption of ions also increases.
266 (c)
Both phenyl mercuric acetate (PMA) and
abscisic acid (ABA) act as antitransirants.
267 (b)
The vertical conduction of water from root to
aerial parts of plant is called ascent of sap.
The water molecules remain joined to each
other due to a force of attraction called
cohesion force. Attraction between water
molecules and the walls of xylem is due to
adhesion force. These factors help to ensure
the continuity of water column in xylem.
268 (b)
In the process of diffusion, electrical charges of
diffusing substances, i.e., +ve charge, affects the
rate of diffusion. Channel protein allows diffusion
of solute or substance of appropriate size, i.e., rate
of diffusion also affected by molecular size of
diffused materials and solubility of diffusing
substances. In lipids these is another factor that
affects the rate of diffusion
269 (d)
Cohesion-tension theory for ascent of sap was
originally proposed by Dixon and Jolly (1894)
and greatly supported and elaborated by
Dixon (1914, 1924). It is also called
transpiration pull theory and is based on the
assumptions of:

Continuous water column from rot
hairs to the tip of the plant.
Cohesive and adhesive properties of
water molecules.
Strong transpiration pull exerted by all
the transpiring leaves on the stem.
270 (a)
According to active K+ theory of Levitt,
opening of stomata occurs due to influx of
K+into guard cells. The source of K+ions are
nearby subsidiary and epidermal cells.
271 (b)
Decrease in CO2 concentration and less H+
ion concentration is responsible for opening
of stomata.
272 (a)
The most accepted theory of ascent of sap is
transpiration pull theory or cohesion-tension
theory proposed by Dixon and Jolly (1894).
This theory states that water forms a
continuous column from root to leaf through
xylem ducts. The loss of water from
mesophyll by transpiration creates
transpiration pull or tension which is
transmitted downwards. The column of
xylem resists breaking due to force of
cohesion between water molecules and
adhesion between water and the wall.
273 (b)
Cohesion tension theory or transpiration pull was
proposed by Dixon and Jolly. Cohesion force is
responsible to produce continuous water column
in tracheary elements while the force of adhesion
between the cells of tracheary elements and water
molecule produce surface tension that accounts
for high capillary through tracheary elements.
Loss of water from aerial parts through
transpiration causes a suction pressure in the

Page| 54

water column of plants and this is known as
transpiration pull
274 (a)
In potato type plant leaf, stomata are more on
the lower surface than the upper surface, e.g.,
potato, pea, tomato, etc.
275 (c)
When a plant is placed in pure water, the water
will move into the cell until the pressure potential
and osmotic potential of the cell become equal
276 (a)
Lenticels are small regions on bark and bear
small, loosely arranged non-chlorophyllous
parenchyma cells called complementary cells.
277 (c)
Cell membrane possesses certain pores, which are
known as porins. These porins are known as
transporter protein and is of two types, carrier
proteins and channel proteins
Carrier proteins bind to the particular solute,
which has to be transported, while channel
proteins are usually gated and allows solute of a
particular size to pass through
278 (b)
In active transport, the movement of solutes occur
against the concentration gradient or chemical
potential gradient with the expenditure of energy
279 (b)
In symplast pathway, the movement of water
from soil to xylem channels takes place from cell
to cell. The cytoplasm of adjacent cells are
connected through plasmodesmata and therefore
water moves from one cell to next cell in symplast
movement
280 (d)
Passive absorption of water by root system is the
result of tension on the cell sap in water column
of xylem. It develops due to transpiration.
Absorption of ions from soil can be by active and
passive transport. C4 photosynthetic system is
found in number of tropical plants, both monocots
and dicot like maize, sugarcane sorghum,
Amaranthus etc. They are called C4-plant because
the first stable photosynthetic product produced
is oxalo acetic acid (4 carbon compound)
281 (d)
According to active K+ theory of Levitt,
opening of stomata occurs due to influx of
K+into guard cells. The source of K+ions are
nearby subsidiary and epidermal cells. The
stomatal closure is considered to be brought
about by exertion of K+and Cl−from the guard
cells to epidermal tissue.
282 (b)
Excessive loss of water from the aerial parts of
plants causes a tension in whole water column of
the plant. As this tension develops due to
transpiration, it is also called as transpirational
pull. Transpirational pull is also called as
cohesion-theory. This theory was proposed by
Dixon and Jolly and at present it is most
acceptable theory for ascent of sap
283 (d)
Levitt (1974) proposed the proton transport
concept to explain the mechanism of opening
of stomata uptake of K+ takes place. The
uptake of K+ is balanced by Cl−uptake. The
malic acid dissociate into hydrogen and
malate ion. The synthesis of malic acid in
guard cells accompanies the influx of
potassium ions.
284 (b)
Transpiration is the manifestation of turgor
pressure. More than 95% of total loss of water
occur through stomata of leaves and the
mechanism of closing and opening of stomata is
regulated by turgidity of guard cells of stomata
285 (c)
Distilled water has the highest water potential.
The value of water potential is always negative or
less than zero. Water potential of a solution is
determined by using pure water as the standard
of reference, which has zero water potential at
normal temperature and pressure.
The presence of solute particles reduce free
energy of the water. Hence, it decreases the water
potential in negative value. So, water potential of
a solution is always less than zero
286 (b)
Carbon dioxide is an effective antitranspirant.
A little rise in CO2 concentration induces
partial closure of stomata. It higher
concentration results in complete closure of
stomata. Light affects the rate of transpiration
in two ways-firstly by controlling the
stomatal opening and secondly by affecting

Page| 55

the temperature. Increase in temperature
increases the rate of transpiration.
287 (d)
During day time, photosynthesis occurs in
guard cells because they contain chloroplast.
The soluble sugar formed by this process
decreases the water potential of guard cells
and hence, resulting in stomatal opening.
288 (b)
Pure water has maximum diffusion pressure. It
solute particles are added in pure water, its
diffusion pressure gets lowered and this
reduction/decrease in diffusion pressure of water
in a solution in reference to its pure state is
termed as diffusion pressure deficit
289 (d)
When an RBC is kept in hypotonic solution
then, water enters the RBC by the process of
osmosis (endosmosis). The RBC will increase
in size and ultimately burst. Osmosis is the
movement of solvent particles from
hypotonic to hypertonic medium through
semi-permeable membrane.
290 (d)
Atmospheric humidity reduces the rate of
transpiration, when the air is dry, the rate of
transpiration increases.
292 (a)
Imbibition.
Air dried seeds of pea on coming in contact with
water can develop an imbibition pressure, which
is mainly responsible for the uptake of water. This
leads to changes in the volume of each seed. Thus,
the lid tightly put over a tin containing seeds with
water will be blown off
293 (a)
The turgidity of cell increases, if water enters
in a cell. As a result of turgidity, turgor
pressure is exerted by its swollen protoplast.
294 (d)
Plants can absorb water through their entire
surface. However, water is found in the soil and
only positively geotrophic part, i.e., root system is
specialised to absorb water. In root system, the
most efficient region of water absorption is the
root hair zone or zone of call differentiation
295 (d)
Root pressure, a manifestation of active water
absorption is a positive pressure, which develops
in the sap of xylem of root of the same plant. It is
observed maximum in rainy season in tropical
plants and during spring in temperate plants. It is
commonly met in plants at around 1-2 atm. It is
absent in gymnosperms. Normally observed value
of root pressure is not able to raise the level of sap
to the top of tree and is only able to raise water
level upto or above ground
296 (a)
Guttation refers to the exudation of water
droplets (in the form of salt solution) from the
margin and tips of leaves. Guttation water is
exuded from the group of leaf cells through
specialised opening or pore structure called
hydathodes or water stomata. It occurs in
herbaceous plants and in some angiosperms like
Colocasia, and tomato. It is finally noticed in the
morning in cereals like oat, wheat and maize. It
takes place when transpiration is suppressed and
relative humidity is high, such as during night
297 (c)
The value of diffusion Pressure Deficit (DPD) is
equal to the difference between the Turgor
Pressure (TP) and the Osmotic Pressure (OP) in a
solution in the cell or system. In full turgid cell
DPD = OP – WP
Or = OP – TP
298 (d)
Transport of organic and inorganic substances in
plants over longer distance proceeds through the
vascular tissue system, i.e., xylem and phloem and
it is called translocation. It occurs through mass
flow
299 (b)
Casparian strips are located in the wall of
endodermal cells. These are made up of lignin and
suberin. They prevent and block the movement of
water and minerals from one side to the other
side via cell wall route. So water cannot reach
through apoplast but it moves through
endodermis by symplastic movement
300 (d)
Mass-flow hypothesis was proposed by
Munch (1931). According to this, food
materials are translocated through phloem
along concentration gradient between food
material(source) to the site of utilization.

Page| 56

301 (c)
Process of diffusion is slow and passive. Diffusion
occurs along the concentration gradient and does
not need energy. In diffusion, molecules diffuse
randomly and the net result being substances
moving from a region of higher concentration to a
region of lower concentration
302 (a)
Movement of water through cell wall is
apoplastic.
303 (d)
Movement of water inside the roots from soil to
xylem and then in most of the plant parts takes
place by transpiration forces, which provides both
energy and necessary pull. Cohesion force is
responsible to join the water molecule with one
another in water column. While force between
tracheary wall and water molecule produces
surface tension which accounts high capillarity
through tracheary elements. These forces help to
ensure the continuity of water column in xylem
304 (c)
Short distance transport of substances like gases,
mineral water, hormones and nutrients occur
through diffusion and by cytoplasmic streaming,
supplemented by active transport
305 (c)
A. Symplastic path
B. Apoplastic path
C. Endodermis
D. Xylem
E. Cortex
F. Casparian strip
G. Pericycle
H. Phloem
306 (b)
This is due to the fact that increased temperature
raises the kinetic energy of the system and lower
temperature works in the opposite direction
308 (a)
The difference between the free energy of
water molecule in pure water and the energy
of water in any other system (solution or
plant tissue) is termed as water potential.
Movement of water occurs from region of
higher water potential to lower water
potential.
Ψw=Ψs+Ψm+Ψp
Where, Ψw=water potential,Ψm=
metric potential
Ψs=solute potential and Ψp=
pressure potential.
309 (b)
Hollard is the amount of total water present in the
soil. Water amount available to the plants is
known as chresard, while echard is the amount of
water, which cannot be absorbed by the plants.
Therefore, it can be summarised as Hollard =
Chresard + Echard
310 (c)
The amount by which diffusion pressure of a
solution is lower than that of its pure solvent
is known as diffusion pressure deficit. When
water enters into the cell TP increases,
turgidity increases and cell wall develops
equal and opposite wall pressure. At the state
of equilibrium, DPD will become zero.
311 (a)
The loss of water from aerial parts of living
plants is known as transpiration.
Transpiration may be stomatal (80-90%),
cuticular (3-9%) and lenticular (0.1%).
Transpiration remain absent in submerged
hydrophytic plants because stomata are
completely absent in the leaves of submerged
plants, e.g., Anacharis and Potamogeton.
312 (a)
The value of osmotic potential of an electrolyte
will be greater by the degree of its dissociation
into ions at a given temperature and dilution over
the one calculated by Van’t Hoffs formula
P = CRT × I or ionisation constant
313 (a)
Co-transport is a method of transport in which
two types of molecule are transported together. It
is of two types, symport method and antiport
method. In antiport method, the molecules are
transported in opposite direction
315 (d)
If an external solution balances the osmotic
pressure of the cytoplasm, it is known as isotonic
solution. When the cells are placed in isotonic
solution, there is no net flow of water
316 (b)
Diffusion of water from its pure state or dilute
solution into a solution or stronger solution,

Page| 57

when the two are separated by semi
permeable membrane is called osmosis. In
thistle funnel experiment, when sugar
solution is added to beaker after the process
of osmosis stops, the solution of beaker
becomes hypertonic, as a result of which
exosmosis occurs in thistle funnel hence, level
of solution in thistle funnel lowers.
317 (a)
Cohesion of water and transpiration pull
theory for ascent of sap is most widely
accepted theory.
318 (a)
Osmosis is a special type of diffusion of water
molecule from a dilute solution to concentration
solution through a differentially or
semipermeable membrane
319 (a)
Guttation refers to the exudation of liquid
drops from margins and tips of the leaves
throught specialized structures called
hydathodes. The development of root
pressure in a plant leads to positive
hydrostatic pressure in xylem sap throughout
the plants. Because water conducting xylem
elements of a vascular bundle terminate in a
hydathodes, xylem sap is forced to flow
throught the hydathodes. Thus in guttation
water is exuded from the leaf.
320 (b)
Potometer is used to measure the rate of
transpiration and it works on the principle that
the amount of water absorbed is equals the
amount of water transpired. Transpiration rate is
inversely proportional to the relative humidity,
i.e., rate to transpiration is lower in higher
relative humidity while lower humidity (dry air)
increases the rate of transpiration
321 (a)
Pea seeds contain protein, while wheat
contains starch, the imbibition capacity of
proteins is more than that of starch. That is
why, pea seeds imbibe more water and show
more swelling than those of wheat grains.
322 (c)
Cytokinins are the plant hormones which play
an important role in the opening of stomata
by the exchange of ions (entry of K+ ions into
guard cells and exit of H+ ions). Cytokinins
are also responsible for the activity of cell
division.
323 (a)
All the statements are correct except IV.
Plasmolysis occurs as simple osmosis process
because water moves from higher concentration
solution to lower concentration solution
324 (b)
To overcome the transport of hydrophilic
substances through membranes, cell membrane
possess aquaporins or water channels. Water
channels have been recorded for passive
transport of water soluble substances made up of
eight different type of aquaporins
325 (a)
Mass flow or pressure flow hypothesis for
translocation of organic food was proposed by
Munch (1930). According to the hypothesis,
organic substances are transported from a higher
osmotic pressure to an area of lower osmotic
pressure. This occurs due to the development of a
gradient turgor pressure. Flow of organic solution
takes place from a region of higher turgor
pressure (source) to an area of lower turgor
pressure (sink) or utilisation site
326 (b)
The auxin treated cells shows an increase in their
metabolism. Respiration in these cells increases
and more of energy is provided for the absorption
of water (active absorption)
327 (d)
The difference between the diffusion pressure
of the solution and its solvents at a particular
temperature and atmospheric conditions is
called DPD (Diffusion Pressure Deficit). DPD
is also known as suction pressure.
In fully turgid cells, turgor pressure is equal
to osmotic pressure and hence diffusion
pressure deficit becomes zero in such case.
OP=TP(in turgid cell)
∴ DPD= 0(zero)
328 (c)
Long distance transport of the substances takes
place through bulk flow system. Organic nutrients
are supplied over long distance transport by
phloem tissue from source to sink region. The
direction of transport of these organic nutrients

Page| 58

can be upward or downward, i.e., bidirectional.
This is due to the variable relationship between
synthesis region or source site and sink or
utilisation region
329 (d)
The cohesion tension theory for ascent of sap
(water movement) in plants was proposed by
Henry Dixon and Jolly (1894) and greatly
supported and elaborated by Dixon (1914,
1924). At present, it is most acceptable theory
for ascent of sap, according to which
continuous water column, cohesion and
adhesion forces and transpiration pull are
responsible for movement of water in the
xylem.
330 (d)
Generally, it is considered that inorganic nutrients
are transported by xylem, while phloem takes
part in transporting organic nutrient. But same is
not true. In xylem sap, nitrogen is also
transported as ions, organic form of amino acids
etc. So, there is an exchange of even a small
amount of material between xylem and phloem. A
majority of minerals enter into the root through
active absorption as concentration of minerals are
more in roots interior then in soil. Relationship
between the source and sink is variable and
depends upon the season and need of plants
331 (a)
Water is a polar molecule and forms hydrogen
bonds between the positively charged hydrogen
atoms and negatively charged oxygen atom.
Hydrogen bonds make water molecules stick
together, a process known as cohesion.
When water molecules form hydrogen bonds with
other molecules, such as carbohydrates, it is
called adhesion. The hydrogen bonds have
tension between them. So water molecules stick
together and move together

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