Respiration in Organisms Class 7 Science Part 2 Chapter 2 Questions With Answers.

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Free Solutions for Assam State Board Class 7 Science Chapter 2 Questions Answers in English Medium

Respiration in Organisms - Questions and Answers

Class 7 Science Part 2 Chapter 2
Assam State Education Board Syllabus 2025-2026 Covered

This chapter explains the process of respiration, different types of respiration, and how organisms breathe. Below are the important questions and answers from NCERT & SCERT Assam Class 7 Science Chapter 2 - Respiration in Organisms, based on the Assam State Education Board syllabus for 2025-2026.

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Introduction to Respiration in Organisms

Respiration is the process by which organisms obtain energy from food.
It can be aerobic (with oxygen) or anaerobic (without oxygen).
The process involves breathing, gas exchange, and energy release.

Class 7 Science Question Answer – Part 2

Below are the chapters of Class 7 Science Part 2. Click on the chapter name to access the respective question-and-answer content:

Respiration in Organisms questions Answers

1. Why does an athlete breathe faster and deeper than usual after finishing the race?

Ans:- Athletes need a lot of energy during the race, and for the release of energy, they need a lot of oxygen; hence they breathe faster than usual after finishing the race.

2. List the similarities and differences between aerobic and anaerobic respiration.

Ans:- Similarities:

1. In both kinds of respiration, food particles are broken down to release energy

2. Both occur inside the cells

3. Both supply by-products

3. Why do we often sneeze when we inhale a lot of dust-laden air?

Ans:- When we inhale dust-laden air, the fine dust particles irritate the nasal passage. To remove these particles, our body triggers sneezing as a reflex action.

4. Take three test tubes. Fill ¾th of each with water. Label them A, B and C. Keep a snail in test tube A, a water plant in test tube B and in C, keep both the snail and plant. Which test tube would have the highest concentration of CO₂?

Ans: Test tube A will have the highest concentration of CO₂because test tube A has a snail which expels out CO₂ into the tube. Since a plant is present in both test tubes B and C, the plant will inhale CO₂ to decrease CO₂ concentration. Thus, there will be less concentration of CO₂ in these tubes.

5. Tick the correct answer:

(a) In cockroaches, air enters the body through

(i) lungs (ii) gills (iii) spiracles (iv) skin

(b) During heavy exercise, we get cramps in the legs due to the accumulation of

(i) carbon dioxide (ii) lactic acid (iii) alcohol (iv) water

(c) Normal range of breathing rate per minute in an average adult person at rest is

(i) 9–12 (ii) 15–18 (iii) 21–24 (iv) 30–33

(d) During exhalation, the ribs

(i) move outwards (ii) move downwards (iii) move upwards (iv) do not move at all

Ans:

a) (iii) spiracles

b) (ii) lactic acid

c) (ii) 15–18

d) (ii) move downwards

6. Match the items in Column I with those in Column II:

7. Mark ‘T’ if the statement is true and ‘F’ if it is false:

(i) During heavy exercise, the breathing rate of a person slows down. (T/F)

(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)

(iii) Frogs breathe through their skins as well as their lungs. (T/F)

(iv) Fishes have lungs for respiration. (T/F)

(v) The size of the chest cavity increases during inhalation. (T/F)

Solution:

i) False

ii) False

iii) True

iv) False

v) True

Class 7 Science Chapter 2 - Important Questions & Answers

Q1: What is respiration?

Answer: Respiration is the biological process in which food (glucose) is broken down in the presence or absence of oxygen to release energy.

Q2: What are the types of respiration?

Answer: There are two types of respiration:

Aerobic respiration – Occurs in the presence of oxygen.
Anaerobic respiration – Occurs in the absence of oxygen.

Q3: Write the equation for aerobic respiration.

Answer: Glucose (C₆H₁₂O₆) + Oxygen (O₂) → Carbon dioxide (CO₂) + Water (H₂O) + Energy (ATP)

Q4: How is anaerobic respiration different from aerobic respiration?

Feature	Aerobic Respiration	Anaerobic Respiration
Oxygen Required	Yes	No
Energy Released	More	Less
End Products	CO₂ & H₂O	Alcohol/Lactic Acid & CO₂

Q5: What is breathing? How is it different from respiration?

Answer: Breathing is the process of taking in oxygen and releasing carbon dioxide. It is a physical process, whereas respiration is a biochemical process that involves the breakdown of glucose to produce energy.

Q6: Explain the role of the diaphragm in breathing.

Answer: The diaphragm is a dome-shaped muscle that contracts and flattens during inhalation, creating space for the lungs to expand and take in air. During exhalation, it relaxes and moves up, pushing air out of the lungs.

Q7: Why do we get muscle cramps after vigorous exercise?

Answer: Muscle cramps occur due to anaerobic respiration in muscle cells. When there is a lack of oxygen, glucose is broken down into lactic acid, which accumulates and causes cramps.

Q8: How do fish breathe underwater?

Answer: Fish breathe through gills, which extract oxygen dissolved in water and expel carbon dioxide.

Q9: How do earthworms breathe?

Answer: Earthworms breathe through their moist skin, allowing oxygen to diffuse directly into their bloodstream.

Q10: Why do we sneeze?

Answer: Sneezing occurs when dust, smoke, or allergens enter our nasal passage. It is a reflex action to clear the irritants from the respiratory tract.

Q11: Why do mountaineers carry oxygen cylinders?

Answer: At high altitudes, the oxygen level is lower. Mountaineers carry oxygen cylinders to compensate for the reduced oxygen availability.

Q12: What is cellular respiration?

Answer: Cellular respiration is the process in which cells break down glucose to release energy in the form of ATP.

Q13: What is the difference between inhalation and exhalation?

Inhalation	Exhalation
Air is taken into the lungs.	Air is expelled from the lungs.
The diaphragm contracts and moves downward.	The diaphragm relaxes and moves upward.
Oxygen enters the bloodstream.	Carbon dioxide is removed from the bloodstream.

Q14: How does respiration take place in plants?

Answer: Plants respire through small openings called stomata, where they take in oxygen and release carbon dioxide.

Q15: How does respiration in amoeba occur?

Answer: Amoeba respires through its cell membrane by diffusion, where oxygen enters and carbon dioxide exits directly.

FAQs on Respiration in Organisms

Q1: Why do we yawn?

Answer: Yawning occurs when the brain needs more oxygen. It helps to increase oxygen intake and remove carbon dioxide.

Q2: Why do animals need more energy than plants?

Answer: Animals move and perform various activities, requiring more energy, whereas plants are stationary and need less energy.

Q3: What is fermentation?

Answer: Fermentation is a type of anaerobic respiration in which microorganisms like yeast break down glucose to produce alcohol and carbon dioxide.

Q4: How do insects breathe?

Answer: Insects breathe through spiracles and tracheal tubes that carry oxygen directly to body tissues.

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