Respiration in Organisms is Chapter 10 taken from JKBOSE and NCERT textbook of Science for students of Class 7th. In the previous post, I provided you with Questions and Answers for Chapter 9 Soil. This post is about Respiration in Organisms Class 7 Question Answers. Before we proceed to Question Answers, you need to have basic information about the chapter you have studied in your classroom reading. So here is a brief overview of the chapter:
Respiration in Organisms Class 7 Question Answers
Overview of Chapter
The following topics are discussed in detail in this chapter:
- WHY DO WE RESPIRE?
- HOW DO WE BREATHE?
- WHAT DO WE BREATHE OUT?
- BREATHING IN OTHER ANIMALS.
- BREATHING UNDER WATER.
- DO PLANTS ALSO RESPIRE?
WHY DO WE RESPIRE? Each cell of an organism performs certain functions such as nutrition, transport, excretion and reproduction. To perform these functions, the cell needs energy. Even when we are eating, sleeping or reading we require energy. The food has stored energy, which is released during respiration. Therefore, all living organisms respire to get energy from food. Respiration is divided into two parts: 1. Breathing 2. Cellular Respiration.
BREATHING: Breathing means taking in air rich in oxygen and giving out air rich in carbon dioxide with the help of respiratory organs. The taking in of air rich in oxygen into the body is called inhalation and giving out of air rich in carbon dioxide is known as exhalation. It is a continuous process which goes on all the time and throughout the life of an organism. The number of times a person breathes in a minute is termed the breathing rate.
HOW DO WE BREATHE? Breathing involves the movement of the diaphragm and the rib cage. 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. The lungs get filled with air. During exhalation, ribs move down and inwards, while the diaphragm moves up to its former position. This reduces the size of the chest cavity and the air is pushed out of the lungs.
WHAT DO WE BREATHE OUT? We breathe our carbon dioxide-rich air from our lungs. This can be demonstrated by passing exhaled air through lime water. It will turn milky. The exhaled air has 16.4% oxygen and 4.4 % carbon dioxide as compared to inhaled air which has 21 % oxygen and 0.04% carbon dioxide.
BREATHING IN OTHER ANIMALS: Animals such as elephants, lions, cows, goats, frogs, lizards, snakes, and birds, have lungs in their chest cavities like human beings. The smaller animals like cockroaches, earthworms, fishes, ants, grasshoppers, mosquitoes, houseflies etc do not have lungs in their chest cavity. They have a different mechanisms for breathing.
- Cockroach: A cockroach has small openings on the sides of its body. Other insects also have similar openings. These openings are called spiracles Insects have a network of air tubes called tracheae for gas exchange.
- Earthworm: The skin of an earthworm feels moist and slimy on touching. Gases can easily pass through them.
BREATHING UNDERWATER: There are many animals which live in the water. The animals living underwater have gills for breathing. Gills are projections of the skin. Gills are well supplied with blood vessels for the exchange of gases.
DO PLANTS ALSO RESPIRE? Like other living organisms, plants also respire for their survival. They also take in oxygen from the air and give out carbon dioxide. In the cells, oxygen is used to break down glucose into carbon dioxide and water as in other organisms.
- Define cellular respiration.
Ans. The process of breakdown of food in the cell with the release of energy is called cellular respiration. It takes place in all the cells of living organisms.
- Why does an athlete breathe faster and deeper than usual after finishing the race?
Ans. Our body needs more energy for activities like running or other heavy exercises. To meet this extra need for energy, the rate of respiration must increase in the cells of our body. Hence, more oxygen is required to meet the energy demand. So, an athlete breathes faster and deeper to inhale more oxygen.
- List the similarities and differences between aerobic and anaerobic respiration.
Ans. Similarities between aerobic and anaerobic respiration are given below:
- Breakdown of glucose takes place in both.
- Energy is released in both types of respiration.
- Both types of respiration take place inside the cell.
- Carbon dioxide is released in both processes.
Differences between aerobic and anaerobic respiration are given below:
|Aerobic Respiration||Anaerobic Respiration|
|1. It takes place in the presence of oxygen.||1. It takes place in the absence of oxygen.|
|2. Glucose is completely broken down into CO2 and water.||2. Glucose is incompletely broken down into ethyl alcohol or lactic acid and CO2|
|3. More energy is released in this process.||3 Less energy is released in this process.|
|4. It takes place in higher organisms like mammals.||4. It takes place in lower organisms like yeast, fungi and bacteria.|
4. Why do we often sneeze when we inhale a lot of dust-laden air?
Ans. When we inhale dust-laden air, dirt particles are captured within the nostrils. Usually, hair in the nasal cavity traps dust particles but sometimes these particles get past the hair in the nasal cavity and irritate the lining of the cavity which is the cause of sneezing. Sneezing helps in expelling foreign particles from inhaled air.
5. Take three test tubes. Fill the 3/4th 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 the snail and plant both. Which test tube would have the highest concentration of CO2?
Ans. In test tube A, the snail is producing CO2 due to the process of respiration.
In test tube B, a water plant is using CO2 for the process of photosynthesis.
In test tube C, the CO2 exhaled by the snail is used by the water plant for photosynthesis.
So, the concentration of CO2 is highest in test tube A.
6. Tick mark the correct answer:
(a) In cockroaches, air enters the body through
Ans. iii) Spiracles
(b) During heavy exercise, we get cramps in the legs due to the accumulation of
(i) carbon dioxide
(ii) lactic acid
Ans. (ii) lactic acid
(c) Normal range of breathing rate per minute in an average adult person at rest is:
Ans. (ii) 15–18
(d) During exhalation, the ribs
(i) move outwards
(ii) move downwards
(iii) move upwards
(iv) do not move at all
Ans. (ii) move downwards
7. 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|
|g) Cockroach||vii) Tracheae|
|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|
|g) Cockroach||vii) Tracheae|
- 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. (False)
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (False)
(iii) Frogs breathe through their skins as well as their lungs. (True)
(iv) Fishes have lungs for respiration. (False)
(v) The size of the chest cavity increases during inhalation. (True)
- Given below is a square of letters in which are hidden different words related to respiration in organisms. These words may be present in any direction— upwards, downwards, or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square:
(i) The air tubes of insects
(ii) Skeletal structure surrounding the chest cavity
(iii) Muscular floor of the chest cavity
(iv) Tiny pores on the surface of the 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 a tracheal system
- The mountaineers carry oxygen with them because:
(a) At an altitude of more than 5kmthere 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 on the ground.
(d) The pressure of air is higher than that on the ground.
Ans. (b) The amount of air available to a person is less than that available on the ground.
- Give two examples of each of the following:
(1) Animals that breathe through gills __________________
(2) Animals that breathe through spiracles __________________
(3) Animals that breathe through skin __________________
Ans. (1) Animals that breathe through gills are Fish and frogs.
(2) Animals that breathe through spiracles are cockroaches and Ants.
(3) Animals that breathe through the skin are Earthworm and Skin.