Class 7 Science Chapter 9 Respiration in organisms Oxford Book Solutions

       Class 7 Ch 9 Respiration in Organisms

       Page 139 – Objective Type Questions

  1. Fill in the blanks with the correct words:

1. A series of (physical/chemical) reactions result in the release of energy by oxidation of food.

2. When the diaphragm…….(contracts/expands) oxygen-rich air is taken into the lungs.

3. The wind pipe is made up of several ring-like structures, held together by ………..(muscles/cartilage).

4. Plant roots typically take in…………spaces between soil particles and give off.

5………….. (Aerobic/Anaerobic) respiration is the most efficient form of respiration.

(oxygen/carbon dioxide) available in small  (oxygen/carbon dioxide).

  1. Ans: A series of chemical reactions result in the release of energy by oxidation of food.
  2. When the diaphragm contracts, oxygen-rich air is taken into the lungs.
  3. The windpipe and pipe is made up of several ring-like structures, held together by cartilage.
  4. Plant roots typically take in oxygen available in small spaces between soil particles and give off carbon dioxide.
  5. Aerobic respiration is the most efficient form of respiration.

B. Choose the correct option.

1. Which of these are like slits and are made up of thread-like structures?

a. Gills                         b. Filaments

c. Capillaries               d. All of these

2. Which of these carries the inhaled air into tiny air bags in human beings?

a. Trachea                   b. Bronchi

c. Bronchioles                        d. Larynx

3. Which of these carries oxygenated blood from the lungs to the heart?

a. Bronchus                b. Pulmonary artery

c. Pulmonary vein     d. Alveoli

4. Which of these is formed as a result of respiration in plants?

a. Energy                    b. Carbon dioxide

c. Water                      d. All of these

5. Which of these is formed as a result of anaerobic respiration?

a. Energy                                            b. Carbon dioxide

c. Energy and ethyl alcohol     d. Energy, carbon dioxide, and ethyl alcohol

6. Which of these refers to breathing?

a. Intake of air rich in oxygen

b. Breakdown of food to produce water and carbon dioxide

c. Releasing energy from the breakdown of food

d. All of these

7. Which of these do amphibians use to breathe in air on land?

a. Trachea                               b. Spiracles

c. Surface of the skin             d. Lungs

8. Which of these helps to pull in oxygen-rich air into the lungs?

a. Expansion of the diaphragm                    b. Relaxation of the diaphragm

c. Up and down movement of the ribs       d. Tracheal tubes

9. Why do farmers plough the soil?

a. To increase root respiration

b. To decrease root respiration

c. To increase respiration through stomata

d. To decrease respiration through stomata

10. Which of these is true about anaerobic respiration?

a. It is carried out in humans for a short time.

b. It takes place in our muscle cells when we are doing heavy work or exercise, running fast, etc.

c. It is common in many micro-organisms.

d. All of these

Ans:

  1. Which of these carries the inhaled air into tiny air bags in human beings?
    Answer: c. Bronchioles
  1. Which of these carries oxygenated blood from the lungs to the heart?
    Answer: b. Pulmonary vein
  2. Which of these is formed as a result of respiration in plants?
    Answer: d. All of these
  3. Which of these is formed as a result of anaerobic respiration?
    Answer: d. Energy, carbon dioxide, and ethyl alcohol
  4. Answer: d Energy, Carbon di oxide and eyhyl alcohol
  5. Which of these refers to breathing?
    Answer: a. Intake of air rich in oxygen
  6. Which of these do amphibians use to breathe in air on land?
    Answer: c. Surface of the skin
  7. Which of these helps to pull in oxygen-rich air into the lungs?
    Answer: c. Up and down movement of the ribs
  8. Why do farmers plough the soil?
    Answer: c. To increase respiration through stomata
  9. Which of these is true about anaerobic respiration?
    Answer: d. All of these

Very Short Answer Type Questions:

  1. Animals in which exchange of gases takes place directly from the water or air through diffusion:
    Examples: Earthworm, Hydra
  2. Animals that breathe through spiracles:
    Examples: Cockroach, Grasshopper
  3. Animals that breathe through their moist skin as well as their lungs:
    Examples: Frog, Salamander
  4. Organisms that respire anaerobically:
    Examples: Yeast, Certain bacteria

III. Short Answer Type Questions:

  1. Define respiration. Why is it called a chemical process?
    Respiration is the process by which energy is released from the breakdown of food (glucose) in cells. It is a chemical process because it involves chemical reactions that produce new substances and energy.
  2. How does the diaphragm help in pumping air?
    The diaphragm contracts and moves downward during inhalation, creating space in the chest cavity for air to enter. It relaxes and moves upward during exhalation, pushing air out of the lungs.
  3. What is oxyhaemoglobin?
    Oxyhaemoglobin is the compound formed when oxygen binds with haemoglobin in the red blood cells. It transports oxygen from the lungs to different parts of the body.
  4. Why do roots of plants need to respire?
    Roots respire to produce energy for growth and absorption of water and minerals from the soil. They take in oxygen from air spaces in the soil.

IV. Long Answer Type Questions:

  1. Explain how a fish respires in water, with the help of gills.
    Fish take in water through their mouths and force it over the gills. Gills have many blood vessels. Oxygen from the water diffuses into the blood through the thin walls of the gills, and carbon dioxide moves out. This process allows fish to breathe underwater.
  2. Describe how exchange of gases takes place inside the human respiratory system.
    Inhaled air travels through the nose, trachea, bronchi, bronchioles, and reaches the alveoli. Oxygen from alveoli diffuses into the blood, and carbon dioxide from blood diffuses into alveoli to be exhaled. This gas exchange takes place in the alveoli due to their thin walls and rich blood supply.
  3. What is the difference between aerobic and anaerobic respiration? Write the equations to show both the processes.

Aerobic Respiration:

Takes place in presence of oxygen.

Glucose + Oxygen → Carbon dioxide + Water + Energy

Equation:

Anaerobic Respiration:

*Takes place in absence of oxygen.

*Glucose → Alcohol + Carbon dioxide + Energy (in yeast)

*Equation:

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