NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms

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class 7 science chapter 10 respiration in organisms
class 7 science chapter 10 respiration in organisms

NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms, here we are going to give you a summary of NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms with questions and answers from the textbook. In this chapter, we will study the meaning of respiration and the different respiration in different organisms. Your all doubts from the chapter NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms will be cleared from this. Breathing is a part of respiration. Let us learn about respiration.

Read more: NCERT Solutions for Class 7 Science Light

Table of Contents

NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms: Introduction

The food has stored energy, which is released during respiration. Respiration is important because it gives our body energy which is used to do important tasks like nutrition, transport, excretion, and reproduction. Therefore, all living organisms respire to get energy from food. The oxygen that we breathe in is important because it helps in the breakdown of food which releases energy in our body. The process of breakdown of food in the cell with the release of energy is called cellular respiration. Cellular respiration takes place in the cells of all organisms.

Different types of respiration.

  1. Aerobic respiration: Food is broken down into carbon dioxide and water using oxygen is called aerobic respiration.
  2. Anaerobic respiration:  Food is broken down into carbon dioxide and water without using oxygen is called anaerobic respiration. 

Breakdown of food releases energy.

Glucose (With the use of oxygen ) → carbon dioxide + water + energy 

Anaerobes: Organisms that can survive in the absence of air are called anaerobes, eg. yeast. They use anaerobic respiration to get energy.

In the absence of oxygen, glucose breaks down into alcohol and carbon dioxide as given below:

Glucose (Without the use of oxygen) →  alcohol + carbon dioxide + energy

NOTE: Yeasts are single-celled organisms. They respire anaerobically and during this process yield alcohol. They are, therefore, used to make wine and beer.

Anaerobic respiration in our muscles

Anaerobic respiration also happens in our muscles but only for a short time, when there is a  temporary lack of oxygen in situations like long hours of heavy exercise, fast running, cycling, walking for many hours or heavy weight lifting. This is because in these situations demand energy is high. But the supply of oxygen to produce the energy is limited. Thus anaerobic respiration takes place. 

Glucose(in muscle) (in the absence of oxygen) → lactic acid + energy

Due to this anaerobic respiration in our muscles, cramps occur.

The partial breakdown of glucose produces lactic acid. Accumulation of this lactic acid causes muscle cramps. Hot water bath or massage improves the circulation of blood and the supply of oxygen to the muscle cells increases.  The increase in the supply of oxygen results in the complete breakdown of lactic acid into carbon dioxide and water and thus we get relief from muscle cramps after a hot massage. 

NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms: Human respiratory system.
Human respiratory system.

BREATHING

Let us perform an activity to understand breathing deeply.

ACTIVITY 1 – NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms

  • Let us close our nostrils and mouth tightly and look at a watch. 
  • What did you feel after some time? How long were you able to keep both of them closed? 
  • Note down the time for which you could hold your breath 

At most it is 30 seconds and up to 2 minutes

We know that we cannot survive for long without breathing.

Breathing means taking in air rich in oxygen and giving out air rich in carbon dioxide with the help of respiratory organs.

Inhalation is  taking in of air rich in oxygen into the body

Exhalation is  giving out of air rich in carbon dioxide

It is a continuous process all the time and throughout the life of an organism. 

Breathing rate: number of times a person breathes in a minute

During breathing inhalation and exhalation take place alternately.

Let us find out if breathing is constant or it changes according to the requirement of oxygen by the body

ACTIVITY 2 – NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms

  • Generally we are not aware that we are breathing. 
  • However, if you try you can count your rate of breathing. 
  • Breathe in and out normally. 
  • Let us find out how many times we breathe in and breathe out in a minute? 
  • Did you inhale the same number of times as you exhaled? 

Now count your breathing rate (number of breaths/minute) after brisk walk and after running. Record your breathing rate as soon as you finish and also after complete rest. 

Observation: We realise that whenever a person needs extra energy, he/she breathes faster. As a result more oxygen is supplied to our cells. It speeds up the breakdown of food and more energy is released.

Activity 3 – NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms

Can we say in which activity, the rate of breathing will be the slowest and in which it will be the fastest? Let us assign numbers to the pictures in the order of increasing rate of breathing according to our experience.

NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms : assign numbers to the pictures
assign numbers to the pictures

HOW DO WE BREATHE?

Let us now learn about the mechanism of breathing.

We take in air through our nostrils generally. we inhale air, it passes through our nostrils into the nasal cavity. 

The air then reaches our lungs through the windpipe.

Lungs are present in the chest cavity (This cavity is surrounded by ribs on the sides.)

 A large, muscular sheet called a diaphragm forms the floor of the chest cavity.

INHALATION

 Breathing involves the movement of the diaphragm and the rib cage

 ribs move up and outwards and the diaphragm moves down during inhalation.

This movement increases space in our chest cavity and air rushes into the lungs.

The lungs get filled with air.

EXHALATION

Ribs move down and inwards, while the diaphragm moves up to its former position.

This reduces the size of the chest cavity and air is pushed out of the lungs and air is exhaled. 

Inhalation and Exhalation :  NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms
Inhalation and Exhalation

ACTIVITY 4 – NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms

  • Let us understand the mechanism of breathing by a simple model.
  • We take a wide plastic bottle. Let us remove the bottom and get a Y-shaped glass or plastic tube. We make a hole in the lid so that the tube may pass through it. 
  • To the forked end of the tube we fix two deflated balloons. We introduce the tube into the bottle as shown in. Now we cap the bottle, seal it to make it airtight. To the open base of the bottle we tie a thin rubber or plastic sheet using a large rubber band.
  • We pull the rubber sheet from the base downwards and watch the balloons. 
  • Next, we push the rubber/plastic sheet up and observe the balloons. 

Did you see any changes in the balloons? 

Ans. Yes, we see changes in the balloons.

What do the balloons in this model represent? 

Ans. Lungs

What does the rubber sheet represent?

Ans. Diaphragm

 NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms : ACTIVITY 4 representation
ACTIVITY 4 representation

WHAT DO WE BREATHE OUT?

Let us see what we breathe out with an activity.

Activity 5 – NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms

  • We take a slender, clean test tube or a glass/plastic bottle. 
  • We make a hole in its lid and fix it on the bottle and pour some freshly prepared lime water in the test tube.
  • Let us insert a plastic straw through the hole in the lid in such a way that it dips in lime water. Now we blow gently through the straw a few times. 

Is there a change in the appearance of lime water? 

Ans. Yes

 What do we exhale?

Ans. We exhale carbon dioxide and a mixture of gases along with it.

BREATHING IN OTHER ANIMALS

Animals such as elephants, lions, cows, goats, frogs, lizards, snakes, birds, have lungs in their chest cavities like human beings.

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. Oxygen rich air rushes through spiracles into the tracheal tubes, diffuses into the body tissue, and reaches every cell of the body. Similarly, carbon dioxide from the cells goes into the tracheal tubes and moves out through spiracles. These air tubes or tracheae are found only in insects and not in any other group of animals.

NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms : Cockroach respiratory system
Cockroach respiratory system

Earthworm: Earthworms breathe through their skins. The skin of an earthworm feels moist and slimy on touching. Gases can easily pass through them. Though frogs have a pair of lungs like human beings, they can also breathe through their skin, which is moist and slippery.

BREATHING UNDER WATER : NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms

Gills in fish help them to use oxygen dissolved in water. They are projections of the skin.  The gills are well supplied with blood vessels for exchange of gases.

Underwater respiration
Underwater respiration

Respiration in organisms class 7

Cellular respiration occurs within the cells of all living organisms. Cells are the place where it is where food (glucose) can be broken in carbon dioxide as well as water by the use of oxygen. When glucose is broken down through the use of oxygen, it is known as aerobic respiration. The food can be also broken down without oxygen.

 Respiration in Plants

Plants 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. In plants each part can independently take in oxygen from the air and give out carbon dioxide. The leaves of the plants have tiny pores called stomata for exchange of oxygen and carbon dioxide.

Like all other living cells of the plants, the root cells also need oxygen to generate energy. Roots take up air from the air spaces present between the soil particles 

Root respiration
Root respiration

NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms : Conclusion

Respiration is essential for survival of living organisms. It releases energy from the food. Respiration is a vital biological  process. All living organisms need to respire to get the energy needed for their survival. Let us now do exercises from NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms.

NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms : Exercises 

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

Ans. An athlete needs a lot of energy running in a race, and thus a lot of energy needs to be released. So they need to respire faster and so they breathe faster and deeper than usual after finishing the race.

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

aerobicanaerobic
Needs OxygenDoesn’t Need Oxygen
Carbon dioxide and water producedCarbon dioxide and alcohol produced
Occurs in most multicellular organisms.Occurs in most unicellular organisms and yeast.
differences between aerobic and anaerobic respiration. 

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

Ans. The nasal tract has fine hairs which get triggered when we inhale a lot of dust-laden air thus we sneeze.

4. Take three test-tubes. Fill 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 snail and plant both. Which test-tube would have the highest concentration of CO2? 

Ans. Test tube A would have the highest concentration of CO2.

5. Tick the correct answer: 

(a) In cockroaches, air enters the body through

 (i) lungs 

(ii) gills 

(iii) spiracles 

(iv) skin 

Ans. (iii) spiracles 

(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

Ans. (ii) lactic acid 

(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

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 

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. 
Question

Ans.

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 
Answer

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) 

Ans. False

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

Ans. False

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

Ans. True

(iv) The fishes have lungs for respiration. (T/F) 

Ans. False

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

Ans. 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 ó 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

Ans. Trachea

(ii) Skeletal structures surrounding chest cavity

Ans. Ribs

(iii) Muscular floor of chest cavity

Ans. Diaphragm

(iv) Tiny pores on the surface of leaf

Ans. Stomata

(v) Small openings on the sides of the body of an insect

Ans. Spiracles

(vi) The respiratory organs of human beings

Ans. Lungs

(vii) The openings through which we inhale

Ans. Nostrils

(viii) An anaerobic organism

Ans. Yeast

(ix) An organism with a tracheal system 

Ans. Ant

9. 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.

Ans. (b) The amount of air available to a person is less than that available on the ground. 

FAQ : NCERT Solutions For Class 7 Science Chapter 10 Respiration in Organisms

Why do we sneeze when we inhale dust laden air ?

We frequently sneeze when breathe in a lot of dusty air to get rid of the external particles. The particles travel through the nasal hair cavity and can cause irritation to the lining of our nasal cavity and trigger a signal for the brain. The brain tells the nasal cavity to start breathing by sneezing.

The openings through which we inhale ?

Nose that opens through which we breathe in air.
Our noses are the part of our body that allows us to breathe air or inhale it.

Why do we often sneeze ?

We frequently sneeze when breathe in a lot of dusty air to eliminate those external particles. These particles pass through the nasal hair chamber and cause irritation to the lining of our nasal cavity and send a signal that the brain. The brain directs the nasal chamber to begin the process of sneezing.

Why do we respire class 7 ?

We breathe to make use of oxygen in order to oxidize the food we eat and to release energy. Similar to burning, however it’s more slowly. It also requires respiratory enzymes .

Why does an athlete breathe faster after finishing a race ?

After getting through the race the participant breathes more quickly and deeper than normal to deliver extra oxygen to cells. Thus, an athlete breathes more quickly and deeply than usual following the finish of the race to increase oxygen levels and thus more energy to the body.

What is the breathing rate class 7?

The number of breaths a person takes in a minute is referred to as the breathing rate. The typical rate of breathing for an adult human at rest is between 15 and 18 minutes per minute

In cockroach air enters the body through ?

A Cockroach has tiny openings on the sides its body, referred to as spiracles. When air is introduced into in the cockroach’s respiratory system via the open spaces the spiracles function as muscle valves which lead to the respiratory system within.

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