Class 11 Biology Chapter 4 Animal Kingdom NCERT Solution

Class 11 Biology Chapter 4 Animal Kingdom is vast and diverse, with millions of species showing a wide range of body structures and functions. In this chapter, we explore how animals are classified based on common features such as levels of organization, body symmetry, presence or absence of body cavity (coelom), patterns of development, and segmentation.

From simple sponges to complex mammals, this chapter helps us understand the structural and functional differences among various animal groups, forming the foundation of biological classification.

Class 11 Biology Chapter 4 Animal Kingdom – Textbook Solution

Intext Questions Answers

1. How do Poriferan animals differ from Coelenterate animals?
Answer:
Poriferans (sponges) are multicellular organisms with a porous body and canal system for water transport. They lack true tissues and symmetry.
Coelenterates (Cnidarians), on the other hand, have a more advanced organization with true tissues, a gastrovascular cavity, and radial symmetry. They possess stinging cells (cnidocytes), which are absent in poriferans.

2. What is the difference between a diploblastic and a triploblastic animal?
Answer:
Diploblastic animals have two embryonic germ layers: ectoderm and endoderm (with a non-cellular mesoglea in between), e.g., Cnidarians.
Triploblastic animals have three germ layers: ectoderm, mesoderm, and endoderm, which allows for more complex tissue and organ development, e.g., Platyhelminthes onwards.

3. Distinguish between intracellular and extracellular digestion.
Answer:

Intracellular digestion occurs inside the cell where food particles are engulfed and digested within food vacuoles, e.g., in Amoeba and sponges.
Extracellular digestion occurs outside the cell in a cavity or digestive tract, where enzymes break down food and the nutrients are absorbed later, e.g., in humans and most animals.

4. What is the advantage of a segmented body?
Answer:
A segmented body allows for greater flexibility and mobility. It also helps in specialization of different segments for different functions like locomotion, reproduction, and digestion. Segmentation is seen in Annelids, Arthropods, and Chordates.

5. How does the symmetry of echinoderms change from larva to adult stage?
Answer:
Echinoderms exhibit bilateral symmetry during their larval stage, which helps in free swimming. However, in the adult stage, they develop radial symmetry (typically pentamerous), which suits their slow-moving or sedentary lifestyle.

NCERT Exercise Questions Answers

1. What are the difficulties that you would face in the classification of animals, if common fundamental features are not taken into account?
Answer:
Without using common features like level of organization, symmetry, body cavity, segmentation, etc., classification would be chaotic and inconsistent. It would be hard to understand relationships among organisms or predict their characteristics, leading to confusion in taxonomy and study.

2. If you are given a specimen, what are the steps that you would follow to classify it?
Answer:
Steps include:

Observe body symmetry (radial or bilateral)
Check presence or absence of coelom
Note segmentation or appendages
Examine the type of digestive, circulatory, and nervous system
Identify embryonic germ layers
Analyze special features like notochord or exoskeleton
This systematic approach helps place the organism into a specific phylum.

3. How useful is the study of the nature of body cavity and coelom in the classification of animals?
Answer:
The type of body cavity (acoelomate, pseudocoelomate, coelomate) is a major classification criterion as it reflects the complexity of organ development. Coelomates have better-developed organ systems, while acoelomates are simpler. This helps in evolutionary classification.

4. Distinguish between intracellular and extracellular digestion.
Answer:
(Already answered in intext Q3; repeat here if required on the page)

5. What is the difference between direct and indirect development?
Answer:

Direct development: The young one resembles the adult, no larval stage is involved (e.g., humans, earthworms).
Indirect development: A larval stage is present which differs from the adult and undergoes metamorphosis (e.g., frog, butterfly).

6. What are the peculiar features that you find in parasitic platyhelminthes?
Answer:

Hooks and suckers for attachment
Flat body for surface adhesion
High reproductive capacity
Protective cuticle
Absence of digestive system (in some, e.g., tapeworm)
These adaptations help them survive inside the host.

7. What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?
Answer:

Segmented body with jointed appendages allows versatility
Hard exoskeleton prevents desiccation
Ability to fly in insects
Variety of habitats (land, water, air)
High reproductive rate
Adaptive radiation led to enormous diversity

8. Water vascular system is the characteristic of which group of the following:
Answer:
(c) Echinodermata

9. “All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement.
Answer:
Chordates possess notochord, dorsal nerve cord, and pharyngeal slits at some stage. Vertebrates are chordates with a vertebral column. Some chordates like Amphioxus (Cephalochordata) do not have vertebral columns, hence all vertebrates are chordates, but not all chordates are vertebrates.

10. How important is the presence of air bladder in Pisces?
Answer:
The air bladder helps in maintaining buoyancy in bony fishes. It prevents them from sinking without using energy for constant swimming. Cartilaginous fishes lack it and hence must swim constantly to avoid sinking.

11. What are the modifications that are observed in birds that help them fly?
Answer:

Hollow bones (lightweight)
Feathers and wings for lift
Air sacs for efficient respiration
Fused bones for rigidity
High metabolic rate
Streamlined body
These features help birds to adapt to an aerial mode of life.

12. Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?
Answer:
Not usually. Oviparous animals often lay many eggs as many don’t survive. Viviparous animals give birth to fewer young but with higher survival due to internal development and parental care. Hence, numbers differ based on reproductive strategy.

13. Segmentation in the body is first observed in which of the following:
Answer:
(c) Annelida

14. Match the following:

a. Operculum	iv. Cyclostomata
b. Parapodia	vi. Annelida
c. Scales	v. Pisces
d. Comb plates	i. Ctenophora
e. Radula	ii. Mollusca
f. Choanocytes	iii. Porifera

15. Prepare a list of some animals that are found parasitic on human beings.
Answer:

Ascaris lumbricoides (roundworm)
Taenia solium (tapeworm)
Enterobius vermicularis (pinworm)
Wuchereria bancrofti (filarial worm)
Plasmodium vivax (malaria parasite)
Leishmania donovani (causes kala-azar)
Trypanosoma (sleeping sickness – rare human infection)

Class-wise Solutions

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