Respiration in Organisms NCERT Solutions – Class 7 Science Chapter 10

Science is one of the most important subjects to understand the nature of interaction between humans and the environment. But for Class 7, it’s important because respiration is necessary for the survival of living beings. Thus it becomes pretty important to understand this chapter in detail.. Among all the chapters of Science, Respiration in Organisms Class 7 Chapter 10 is one of such vital chapters that lets students learn about the modes in which different organisms respire. As we can understand, this is about our surroundings and living organisms around us, so students must have a  good understanding of this chapter.

NCERT Solutions for Class 7 Science Chapter 10  provides an idea of this whole chapter through detailed answers to the NCERT Chapter 10 textbook questions., making it easy for students to  prepare for the exams without any hassle.

NCERT Solutions for Class 7 Science Chapter 10 

Access NCERT Solutions for Class 7 Science Chapter 10 – Respiration in Organisms

NCERT Solutions for Class 7 Science

In addition to Class 7, Chapter 10, there are solutions available for all the science chapters for Class 7. These solutions can be beneficial for students to score good grades in the exams. . 

  • Chapter 1 – Nutrition in Plants
  • Chapter 2 – Nutrition in Animals
  • Chapter 3 – Fibre to Fabric
  • Chapter 4 – Heat
  • Chapter 5 – Acids, Bases and Salts
  • Chapter 6 – Physical and Chemical Changes
  • Chapter 7 – Weather, Climate and Adaptations of Animals to Climate
  • Chapter 8 – Winds, Storms and Cyclones
  • Chapter 9 – Soil
  • Chapter 10 – Respiration in Organisms
  • Chapter 11 – Transportation in Animals and Plants
  • Chapter 12 – Reproduction in Plants
  • Chapter 13 – Motion and Time
  • Chapter 14 – Electric Current and Its Effects
  • Chapter 15 – Light
  • Chapter 16 – Water: A Precious Resource
  • Chapter 17 – Forests: Our Lifeline
  • Chapter 18 – Wastewater Story

NCERT Solutions for Class 7 Science Chapters

 Students of Class 7 Science Chapter 10. will learn about the complete process of respiration in living organisms. 

10.1 Why do we respire?

Every cell in an organism performs multiple functions including nutrition, transportation, excretion, reproduction, and more. They need energy for this. The food in the body is stored energy that is released during respiration.

Understanding Respiration

We breathe in oxygen and breathe out carbon dioxide. The air that is rich in oxygen is transported to all the parts of the body, and reaches every cell. It is this oxygen that cells utilise for respiration. The process of breaking down food in the cells with the release of energy is known as cellular respiration.

Aerobic respiration

When the glucose breaks down using the oxygen, it is called aerobic respiration. The glucose breaks down into carbon dioxide and water while releasing energy. The aerobic respiration takes place in mitochondria. Aerobic respiration occurs in most organisms including humans, lions, cats, dogs, goats, earthworms, fishes etc.

Formula for aerobic respiration:

Glucose (Food)     Oxygen Carbon dioxide + Water + Energy

Anaerobic respiration

When the glucose breaks down without using oxygen, it is called anaerobic respiration. In this type of respiration, glucose doesn’t break down completely into carbon dioxide and water. A smaller amount of energy is released during the process, forming an intermediate compound. 

Anaerobic respiration occurs in yeast such as Saccharomyces cerevisiae and some other bacteria.

Formula for anaerobic respiration:

Glucose (Food) No oxygen or air Alcohol + Carbon dioxide + Energy

Anaerobic Respiration in Muscles

Aerobic respiration usually takes place in humans, but it can also occur in muscles for a short time due to temporary deficiency of oxygen. When our body performs heavy exercises such as walking, running, weight lifting etc., it requires a large amount of energy. Anaerobic respiration occurs to meet the energy requirement of the muscle cells. Partial breakdown of glucose or food in muscle cells occurs during this process in the absence of oxygen, forming lactic acid and releasing extra energy.

Here’s the formula showing the production of lactic acid:

Glucose (Food) absence of oxygen Lactic acid + Extra energy

10.2 Breathing

As we discussed, we inhale oxygen and exhale carbon dioxide, and this process is called inhalation and exhalation, respectively. This inhalation and exhalation process continues throughout the life of all living organisms. Both the processes occur altogether, and thus the complete procedure is called breathing.

Breathing rate is the number of times a person breathes in one minute. On an average an adult breathes in and out 15-18 times a minute. The breathing rate changes as per the body’s oxygen requirement and therefore is not constant. For instance, while working out, a person requires more oxygen, whereas while sitting, the same person requires less oxygen; hence in both conditions breathing rate will be different. During heavy workout, the breathing rate can go up to 25 times per minute.Faster breathing increases oxygen supply to our cells and it speeds up the breakdown of  food and more energy is released., w

10.3 How do we breathe? 

  • We breathe through the nostrils.

  • We inhale air that passes through the nostrils into the nasal cavity.

  • From the nasal cavity, it reaches lungs through the windpipe.
  • Lunges are present in the chest cavity, and this cavity is surrounded by ribs on the sides.
  • Diaphragm, a large muscular sheet forms the floor of the chest cavity.

On the other hand, during exhalation, the ribs move down and inward, and the diaphragm comes back to its original position. Thus the space in the chest cavity is reduced, and the air is pushed out.

Breathing in (Inhalation)

Two processes occur together when we breathe in (inhale): the muscles between the ribs contract, as a result the ribcage moves upward and outward and diaphragm contracts moving downwards. This upward and downward movement of the diaphragm and ribcage increases the space in the chest cavity, making it larger. When the chest cavity becomes larger, it sucks air and lungs get filled up with air and expand.

Breathing out (Exhalation)

Reverse process takes place, when we breathe out. The ribcage moves downward and inward, while the diaphragm moves upward. This movement decreases the space in the chest cavity, making it smaller. The air is pushed out of the lungs, when the chest cavity becomes smaller.

10.4 What do we breathe out?

The breathing out process is called exhalation, and when we exhale, the exhaled air or gas generally consists of carbon dioxide. Along with this, oxygen and water vapours are also present. When we exhale air on the mirror or glass, a moisture film gets produced. Inhaled air carries 21% oxygen and 0.04% carbon dioxide. Exhaled air carries 16.4% oxygen and 4.4% carbon dioxide.

Doing the traditional breathing exercise called pranayama every day can increase the capacity of lungs to take in more air. As a result, more oxygen will be supplied to the body cells, which will lead to release of more energy.

10.5 Breathing in other animals

Like human beings, other creatures like elephants, snakes, frogs, cows, and birds also inhale through lungs present in their chest cavities. Though, some other organisms use distinct modes of respiration.  

Cockroach: Little openings on the sides of cockroaches are called spiracles. Other insects also have spiracles. The spiracles are attached to the trachea, a network of several air tubes that work in gaseous exchange. Oxygen inhaled through spiracles gets infused into the rest of the body via these tracheal tubes. Carbon dioxide is transmitted from different cells in the tracheal tube in the same way and is exhaled through the spiracles. This mode of respiration is present only in insects. 

Earthworms: Skin is the respiratory organs of an earthworm. Their skin is moist and allows gas to pass through it. A similar respiration mode occurs in frogs, but they have lungs like human beings.

10.6 Breathing under water

Living organisms can also breathe and survive underwater. For example, fishes possess gills to breathe in the water. Gills have blood vessels   and allow gaseous exchange.

10.7 Do plants also respire?

Plants also respire just like any living organism. Stomata is the part that is involved in the gaseous exchange in plants. Plants inhale oxygen and exhale carbon dioxide. Oxygen helps in the breakdown of glucose, and thus water and carbon dioxide are released.

Key Features of NCERT Solutions for Class 7 Science Chapter 10

NCERT Solutions for Class 7 Science Chapter 10 offers many benefits to students of Class 7 in understanding and learning the Class 7 Science Chapter 10 question answer. Here are a few reasons to refer to NCERT Solutions for Class 7 Science Chapter 10 by Extramarks:

  • The solutions have answers to all the textbook questions.
  • The answers are written in simple language.
  • The subject matter experts who have years of experience have prepared these solutions in accordance with NCERT textbooks and CBSE guidelines.
  • The solutions can  be used for last minute revision as these notes make it easier for students  to remember the main points easily and quickly. 

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


The body of an athlete, who runs in a race, requires more oxygen. Therefore, his breathing rate increases so as to supply more oxygen to the body cells. This is why an athlete, after finishing the race, breathes deeper and faster than usual.

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


Similarities between aerobic and anaerobic respiration are:
1. Energy is produced.
2. Carbon dioxide is released.

Differences between aerobic and anaerobic respiration are:

Aerobic Respiration Anaerobic Respiration
1. It takes place using oxygen. 1. It takes place without using oxygen.
2. It releases large amount of energy. 2. It releases small amount of energy.
3. Water and carbon dioxide are produced. 3. Alcohol and carbon dioxide are produced.


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

We often sneeze on inhaling dust-laden air because dust particles get entangled in the hair present in the nostrils which irritate the nasal membrane and cause sneezing. Hair found in the nostrils prevents entry of dust particles into lungs and sneezing expels them from the nose, allowing only clean air to enter the lungs.

Q.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 snail and plant both. Which test-tube would have the highest concentration of CO2?


All the organisms produce carbon dioxide and water as the final products of respiration.
Test tube A will have the highest concentration of CO2 because the snail kept in it produces carbon dioxide by the process of respiration. On the other hand, test tube B will have the least concentration of carbon dioxide among the three because the water plant performs photosynthesis during which carbon dioxide is utilised and oxygen is produced. In the test tube C, carbon dioxide produced by the snail and by the plant is used up in the process of photosynthesis performed by the plant.

Q.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


(a) In cockroaches, air enters the body through (iii) spiracles.
(b) During heavy exercise, we get cramps in the legs due to the accumulation of (ii) lactic acid.
(c) Normal range of breathing rate per minute in an average adult person at rest is: (ii) 15-18.
(d) During exhalation, the ribs (ii) move downwards.

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

Column I Column II
(a) Yeast (i) Earthworm
(b) Diaphragm (ii) Gills
(c) Skin (iii) Alcohol
(d) Leaves (iv) Chest cavity
(e) Fish (v) Stomata
(f) Frog (vi) Lungs and skin
(vii) Tracheae


The correctly matched contents of Column I with Column II are as follows:

Column I Column II
(a) Yeast (iii) Alcohol
(b) Diaphragm (iv) Chest cavity
(c) Skin (i) Earthworm
(d) Leaves (v) Stomata
(e) Fish (ii) Gills
(f) Frog (vi) Lungs and skin

Q.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) The fishes have lungs for respiration. (T/F)
(v) The size of the chest cavity increases during inhalation. (T/F)


(i) False
(ii) False
(iii) True
(iv) False
(v) True

Q.8 The mountaineers carry oxygen with them because:
(a) At an altitude of more than 5 km there is no air.
(b) The amount of air available to a person is less than that available on the ground.
(c) The temperature of air is higher than that on the ground.
(d) The pressure of air is higher than that on the ground.


The mountaineers carry oxygen with them because:
(b) The amount of air available to a person is less than that available on the ground.



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FAQs (Frequently Asked Questions)

1. How many topics are there in the Class 7 Science Chapter 10?

Various topics covered in NCERT Class 7 Science Chapter 10 are:

  1. Why Do We Respire?
  2. Breathing
  3. How Do We Breathe?
  4. What Do We Breathe Out?
  5. Breathing in Other Animals
  6. Cockroach
  7. Earthworms
  8. Breathing Underwater
  9. Do Plants also Respire?

2. What are the differences between anaerobic and aerobic respiration?

Here are the differences between anaerobic and aerobic respiration:

Aerobic respiration

  • It takes place in the presence of oxygen
  • Food breaks down completely in aerobic respiration
  • CO2 and water are end products of aerobic respiration
  • A large amount of energy is produced during aerobic respiration

Anaerobic respiration

  • Takes place in the absence of oxygen
  • Food breaks down partially in anaerobic respiration
  • Alcohol and CO2 or lactic acid are end products of anaerobic respiration
  • Less amount of energy is products during anaerobic respiration

3. How to study the Science subject in Class 7?

Students can register with Extramarks to access  the NCERT Solutions  and study these solutions chapter wise. Learn all the salient points described in the solutions as these are taken  from the chapter itself to help them understand the key points and make them revise quickly.