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NCERT Solutions for Class 7 Science Chapter 6 Respiration in Organisms
Edited By Irshad Anwar | Updated on May 22, 2025 12:32 PM IST
Class 7 Science Chapter 6, Respiration in Organisms, describes a crucial process by which living organisms obtain energy by decomposing food with the help of oxygen. This chapter teaches how different organisms breathe and how oxygen helps release the energy needed for survival. NCERT Solutions for Class 7 discuss both aerobic respiration, i.e., utilising oxygen, and anaerobic respiration, i.e., without oxygen.
This Story also Contains
- Solved Exercise Questions of NCERT Solutions for Class 7 Science Chapter 6:
- Important Topics of Chapter 6: Respiration in Organisms
- Approach to Solve NCERT Solutions for Class 7 Science Chapter 6 "Respiration in Organisms"
- Important Question on Respiration in Organisms
- NCERT Solutions for Class 7 Science Chapter-Wise
For easier understanding of these concepts, the NCERT Solutions for Class 7 Science Chapter 6 Respiration in Organisms explain things in simple terms, give diagrams, and step-by-step solutions to textbook problems. These NCERT Solutions help students to prepare well for exams and have a strong grip over respiration.
Download PDF of NCERT Solutions for Class 7 Science Chapter 6: Download PDF
You can download the PDF from the link below:
Solved Exercise Questions of NCERT Solutions for Class 7 Science Chapter 6:
The solutions are given in sequence as per the NCERT textbook data:
Q1. Why does an athlete breathe faster and deeper than usual after finishing the race?
Answer:
The muscles of an athlete undergo anaerobic respiration which means the oxygen is used up faster than being supplied by the blood.
Thus, to inhale more oxygen, an athlete breathes faster and deeper than usual after finishing the race.
Q2. List the similarities and differences between aerobic and anaerobic respiration.
Answer:
The similarities between aerobic and anaerobic respiration are:
(i) Carbon dioxide is produced in both reactions.
(ii) Energy is released in both reactions.
The differences between aerobic and anaerobic respiration are:
| Aerobic | Anaerobic |
| Takes place in the presence of oxygen | Takes place without oxygen |
| Complete breakdown of food | Partial breakdown of food |
| Carbon dioxide and water as the end product | Ethanol, carbon dioxide as the end product(in yeast) |
| Produces more energy | Produces less energy |
Q3. Why do we often sneeze when we inhale a lot of dust-laden air?
Answer:
Sneezing removes the foreign particle like dust particles, smoke from the air inhaled which ensures good air quality inside our body.
When we inhale, unwanted particles get trapped in the hair present in our nasal cavity. However, sometimes these particles may get past the hair causing irritation in the lining of the cavity. This causes sneezing.
Answer:
We know,
Snail will inhale oxygen and exhale carbon dioxide whereas the plant will inhale carbon dioxide for respiration.
The test with snail and without plant will have maximum carbon dioxide concentration. Therefore, the order of test tube containing CO2 is A>C>B .
Hence, test-tube A will have the highest concentration of CO2 .
Q5. Tick the correct answer:
(a) In cockroaches, air enters the body through
(i) lungs
(ii) gills
(iii) spiracles
(iv) skin
Answer:
A cockroach has small openings called spiracles on the sides of its body.
Therefore, (a) In cockroaches, air enters the body through (iii) spiracles
(i) carbon dioxide
(ii) lactic acid
(iii) alcohol
(iv) water
Answer:
(b) During heavy exercise, we get cramps in the legs due to the accumulation of (ii) lactic acid
During heavy exercise, muscle cells respire anaerobically because oxygen is used faster as compared to its supply by the blood. The partial breakdown of glucose produces lactic acid whose accumulation causes muscle cramps.
Q5. Tick the correct answer:
(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
Answer:
The normal range of breathing rate per minute in an average adult person at rest is (ii) 15–18
This means on average, an adult human being breathes in and out 15–18 times in a minute.
Q5. Tick the correct answer:
(d) During exhalation, the ribs
(i) move outwards
(ii) move downwards
(iii) move upwards
(iv) do not move at all
Answer:
During exhalation, the ribs (ii) move downwards
During exhalation, ribs move down and inwards reducing the size of the chest cavity causing the air to be pushed out of the lungs.
Q6. 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
Answer:
| 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 |
Q7. 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)
Answer:
(i) During heavy exercise the breathing rate of a person slows down. False
- During heavy exercise, we breathe faster and deeper than usual
(ii) Plants carry out photosynthesis only during the day and respiration only at night. False
- Respiration is an essential process required for the plants to live. It occurs day and night. Whereas, photosynthesis takes place only during the day.
(iii) Frogs breathe through their skins as well as their lungs. True
(iv) The fishes have lungs for respiration. False
- Fishes do not have lungs. They breathe through gills.
(v) The size of the chest cavity increases during inhalation. True
- During inhalation, ribs move up and outwards and the diaphragm moves down. This movement increases space in our chest cavity and air rushes into the lungs.
(i) The air tubes of insects
(ii) Skeletal structures surrounding chest cavity
(iii) Muscular floor of chest cavity
(iv) Tiny pores on the surface of leaf
(v) Small openings on the sides of the body of an insect
(vi) The respiratory organs of human beings
(vii) The openings through which we inhale
(viii) An anaerobic organism
(ix) An organism with tracheal system
Answer:
(i) The air tubes of insects - TRACHEA
(ii) Skeletal structures surrounding the chest cavity - RIBS
(iii) Muscular floor of chest cavity - DIAPHRAGM
(iv) Tiny pores on the surface of the leaf - STOMATA
(v) Small openings on the sides of the body of an insect - SPIRACLES
(vi) The respiratory organs of human beings - LUNGS
(vii) The openings through which we inhale - NOSTRILS
(viii) An anaerobic organism - YEAST
(ix) An organism with the tracheal system - ANT
Q9. 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 the air is higher than that on the ground.
(d) The pressure of air is higher than that on the ground.
Answer:
The mountaineers carry oxygen with them because the amount of oxygen available to a person is less than that available on the ground.
Hence, the correct answer is option (b)
As we move higher in altitude, the density of the atmosphere lessens.
NCERT Solutions for Class 7- Subject Wise
Important Topics of Chapter 6: Respiration in Organisms
Topics and Sub-Topics in Chapter 6: Respiration in Animals and Plants:
| Respiration in Organisms |
| Why do we respire? |
| Breathing |
| How do we breathe? |
| What do we breathe out? |
| Breathing in Other Animals |
| Breathing underwater |
| Do plants also respire? |
Approach to Solve NCERT Solutions for Class 7 Science Chapter 6 "Respiration in Organisms"
Begin by understanding the basic concept of respiration as the process by which organisms take in oxygen and release carbon dioxide to produce energy from food.
Focus on the differences and similarities between aerobic and anaerobic respiration, including their processes, energy yield, and examples of organisms that use each type.
Study the human respiratory system carefully, including the structure and function of organs like the nasal cavity, trachea, lungs, and diaphragm, and understand the mechanics of breathing (inhalation and exhalation).
Use diagrams to visualize the respiratory organs and processes, which will help in answering both diagram-based and descriptive questions accurately.
Practice all exercise questions thoroughly, paying attention to real-life applications such as why athletes breathe faster after exercise and how different organisms respire, to build conceptual clarity and exam readiness.
Also, check the NCERT Books and the NCERT Syllabus here
Important Question on Respiration in Organisms
Question: What are the similarities and differences between plant and animal respiration?
Answer: Both animals and plants respire to release energy from glucose. The process and function of respiration in animals and plants differ, though.
Similarities:
Both plants and animals respire to produce energy (ATP) for the process of life. Oxygen is utilized in the process of aerobic respiration in both animals and plants, and the byproduct is carbon dioxide. Both are the processes of breaking glucose into ATP via the same steps (glycolysis, Krebs cycle, and electron transport chain).
Differences:
Location: Respiration in animals takes place within the mitochondria of all cells, whereas in plants, respiration takes place within all living cells, but a related process of photosynthesis takes place primarily in the chloroplasts of leaves.
Oxygen Utilisation and Carbon Dioxide Exhalation: Animals alone use oxygen and exhale carbon dioxide, while plants utilize oxygen and exhale carbon dioxide during the night when there is no photosynthesis. Plants do photosynthesis during the daytime, taking in carbon dioxide and exhaling oxygen, so they differ from animals in that way.
Production of Energy: Plants generally use respiration to yield usable ATP from stored energy contained in sugars but also use sunlight energy through the process of photosynthesis. Animals, however, entirely rely upon respiration in order to extract energy from sources of food.
NCERT Solutions for Class 7 Science Chapter-Wise
The chapterwise solutions are given below:
Frequently Asked Questions (FAQs)
1. Why does an athlete breathe faster and deeper than usual after finishing a race?
During intense physical activity, muscles require more energy, which is produced by breaking down glucose using oxygen. To meet the increased oxygen demand and remove excess carbon dioxide, athletes breathe faster and deeper after a race.
2. What is the difference between aerobic and anaerobic respiration?
| Aspect | Aerobic Respiration | Anaerobic Respiration |
|---|---|---|
| Oxygen requirement | Requires oxygen | Does not require oxygen |
| End products | Carbon dioxide and water | Carbon dioxide and alcohol (or lactic acid in muscles) |
| Energy produced | Large amount of energy | Less energy compared to aerobic |
| Occurs in | Most plants and animals | Yeast, some bacteria, and muscle cells during heavy exercise |
Both processes break down food to release energy inside cells.
3. How do different organisms respire?
Humans and many animals breathe through lungs.
Fish use gills to extract oxygen dissolved in water.
Earthworms and some amphibians respire through their moist skin.
Insects use a system of tubes called tracheae for respiration.
4. How does respiration take place in humans?
Respiration in humans starts when we take oxygen-rich air into the lungs. Oxygen seeps into the blood and gets distributed to cells, where it assists in decomposing glucose in order to liberate energy. Carbon dioxide is a by-product that gets transferred back to lungs and expelled out.
5. Why is oxygen necessary for respiration?
Oxygen is required for respiration, as it assists in breaking down glucose to generate energy. This is achieved during aerobic respiration within the mitochondria of cells. Cells generate less energy when they lack oxygen and use anaerobic respiration.
6. How does respiration occur in plants?
Plant respiration takes place in every cell, where glucose is fermented with oxygen to release energy. This process mainly occurs in the mitochondria. The energy thus generated maintains growth, repair, and other important functions.
7. How do fish breathe in water?
Fish breathe through water by sucking it in through their mouth and letting it flow over their gills. Gills remove dissolved oxygen from the water and give out carbon dioxide. The oxygen flows into the fish's bloodstream to sustain basic functions.
8. What are the effects of anaerobic respiration in muscles?
Anaerobic respiration in muscles yields energy without the use of oxygen and results in the creation of lactic acid. This accumulation results in muscle fatigue and soreness. It yields rapid energy during hard work but is not as effective as aerobic respiration.
9. Do all living organisms have the same type of respiration process?
No, all living things do not share the same kind of respiration process. Some utilize aerobic respiration with oxygen, while others utilize anaerobic respiration without oxygen. The kind varies depending on the organism and its surroundings.
10. What is respiration?
Respiration is the mechanism through which living things liberate energy from food. It most commonly involves the breakdown of glucose in the presence of oxygen. This energy is utilized for a number of activities of life such as growth, movement, and repair.
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