Respiration in Organisms NCERT Solutions - Class 7 Science

1. Why Does an Athlete Breathe Faster and Deeper than Usual After Finishing the Race?

Ans: Running requires a lot of energy, and ATP is produced by the breakdown of glucose, which is a rapid source of energy. As a result, while running, all of the reserve energy is used, and more oxygen is required for the generation of fresh ATP. As a result, following the race, the athlete breathes faster.

2. List the Similarities and Differences Between Aerobic and Anaerobic Respiration.

Ans: Similarities include: 

i. The release of energy.

ii. Carbon dioxide is released into the atmosphere.

Differences: 

i. Anaerobic feeding occurs in the absence of oxygen, whereas aerobic respiration necessitates the presence of oxygen.

ii. In aerobic respiration, glucose is entirely broken down, but in anaerobic respiration, incomplete oxidation occurs.

3. Why Do We Often Sneeze When We Inhale a Lot of Dust-Laden Air?

Ans: When we inhale air, undesired particles such as dust, dirt, pollen, and smoke enter our respiratory system, causing irritation in the nasal cavity. This causes 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. 

The maximum concentration of carbon dioxide will be found in test tube A. The snail's respiration produces carbon dioxide (CO2). Snail is an organism that takes in oxygen and exhales carbon dioxide. As a result, the concentration of CO2 in test tube A rises.

5. Tick the Correct Answer: 

i. In Cockroaches, Air Enters the Body Through

i. Lungs

ii. Gills 

iii. Spiracles

iv. Skin

Ans: Spiracles

ii. 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: lactic acid

iii. The 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: 15-18

iv. During Exhalation, the Ribs 

i. Move Outwards 

ii. Move Downwards 

iii. Move Upwards

iv. Do Not Move at All.

Ans: Move downwards

6. Match the Items in Column I with Those in Column II 

Ans : 

7. Mark ‘T’ If the Statement is True and ‘F’ If it is False:

1. During Heavy Exercise, the Breathing Rate of a Person Slows Down.

Ans: False, When we exercise, our bodies move, which necessitates more energy to complete the task and enough oxygen for organs to function properly. Following the exercise, a person requires additional carbon dioxide to expel the carbon dioxide produced during the exercise. 

2. Plants Carry Out Photosynthesis Only During the Day and Respiration Only at Night. 

Ans: False, Plants only photosynthesize during the day when the sun is shining, yet they respire all day and night.

3. Frogs breathe through their skins as well as their lungs.

Ans: True.

4. The Fishes have Lungs for Respiration.

Ans: False, The gills allow the fish to breathe. Fishes are devoid of lungs.

5. The Size of the Chest Cavity Increases During Inhalation.

Ans: True.

8. 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 These Words Are Given Below the Square. 

1. The Air Tubes of Insects. 

2. The Skeletal Structure Surrounding the Chest Cavity. 

3. The Muscular Floor of the Chest Cavity. 

4. Tiny Pores on the Surface of the Leaf. 

5. Small Opening on the Sides of the Body of an Insect. 

6. The Respiratory Organ of Human Beings. 

7. The Opening Through Which We Inhale. 

8. An Anaerobic Organism.

Ans : 

9. the Mountaineers Carry Oxygen With Them Because----------------. 

Ans: The amount of air accessible at that altitude is significantly smaller than on land. Therefore, mountaineers carry oxygen with them. 

NCERT Solutions for Class 7 Science – Free PDF Download

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Chapter 10 – Respiration in Organisms

NCERT Solutions for Class 7 Science Chapters

NCERT Grade 7 Science, Chapter 10, Respiration in Organisms is all about respiration, reasons behind respiration, and a few different concepts related to respiration. The first component discusses the motives at the back of breathing. Under this, terms like cell respiration along with the site of cell respiration are defined.

The procedure of breakdown of food with and without the presence of oxygen are explained using chemical equations. The procedure of anaerobic respiration is explained under situations like a breakdown of meals and muscles. The breathing mechanism along with the procedure of inhalation and exhalation is defined in the chapter, Respiration in Organisms. The activity enables us to recognize the changes in breathing rate under one of a kind conditions.

Thereafter, the mechanism of breathing in human beings is significantly defined using diagrams in the chapter, Respiration in Organisms. Focus is likewise given to parts like the nasal cavity, lungs, chest cavity, and diaphragm. Harmful consequences of smoking are mentioned in short. Under the human respiration system, the impact of respiratory at the chest length has defined the usage of pastime and a model showing it diagrammatically. The idea of breathing in animals is mentioned via means of taking examples of cockroaches and earthworms. The procedure of breathing underwater is defined along with a figure depicting different breathing organs of fish. At last respiration in the case of plants is covered in the chapter, Respiration in Organisms.

The chapter, Respiration in Organisms is covered under the following sections:

1. Why Do We Respire?

2. Breathing

3. How Do We Breathe?

4. What Do We Breathe Out?

5. Breathing in Other Animals

6. Breathing Underwater

7. Do Plants Also Respire?

10.1 Why do We Respire

All living organisms are made up of small microscopic building blocks called the cell. The cell is considered to be the smallest functional and structural unit of life. The cell performs all the vital functions of the body like transport, nutrition, respiration, excretion, and reproduction. Cells need the energy to perform all these important functions. The source of this energy is the food that we eat. Food releases energy during the process of respiration.

During respiration, all animals breathe in oxygen and breathe out carbon dioxide. The oxygen that we breathe in is transported to all cells of the body and functions in the processing of food. This processing of food in the cells to release energy is called cellular respiration. During respiration, food is broken down in the presence of oxygen to form energy and carbon dioxide. When glucose is broken down in the presence of oxygen, it is called aerobic respiration. When glucose is broken down in the absence of oxygen, it is called anaerobic respiration. During the breakdown of food, energy is released.

\[\text{Glucose}\xrightarrow{\text{In the presence of oxygen}}\text{Carbon dioxide  +  water  +  energy}\]

However, not all organisms use oxygen in the breakdown of glucose. For example, yeast can survive in the absence of oxygen. This type of organism is called anaerobe. They obtain energy from glucose in the absence of oxygen. The end products of anaerobic respiration are alcohol, carbon dioxide, and energy. 

\[\text{Glucose}\xrightarrow{\text{In the absence of oxygen}}\text{Carbon dioxide  +  alcohol  +  energy}\]

Yeasts are unicellular organisms that produce energy and alcohol by anaerobic respiration. The alcohol thus produced is used in the manufacture of beer and wines. Our muscle cells can also perform anaerobic respiration for a short period when it experiences oxygen deficiency, for example, during running, heavy exercise, walking, cycling, or heavy weight lifting. i.e., when the energy demand of the cells is high.

\[\text{Glucose}\xrightarrow{\text{In the absence of oxygen}}\text{lactic acid  +  energy}\]

Due to the anaerobic respiration of the muscles, muscular cramps develop. Due to the partial breakdown of glucose, lactic acid is produced. Accumulation of lactic acid in the muscles leads to muscle cramps. We get relief from such cramps by massaging those parts or after a hot water bath. Massage or a hot water bath improves blood circulation, and thus improves the oxygen supply to the affected muscles. In the presence of oxygen, lactic acid is converted to carbon dioxide and water.

10.2 Breathing

As discussed earlier, during breathing, we take in oxygen and breathe out carbon dioxide.  Breathing in the air is known as inhalation while giving out the air is called exhalation. The inhalation and exhalation process continues throughout an organism’s life. Both the processes occur simultaneously and together constitute the breathing process.

The number of times a person breathes in a minute is called breathing rate. The breathing rate is not constant but changes often according to the oxygen requirement of the body. For example, during heavy exercise, a person breathes more to meet with the oxygen requirement of the muscles. When the person breathes faster, the oxygen supply to the cells increases, which increases the breakdown of food and release of energy. As a result, the person also feels hungry after any physical activity.

Similarly, when a person feels drowsy, the energy requirement of his cells is low. Therefore, the breathing slows down. The average breathing rate of a person during normal activities is about 15-18 times in a minute. It increases to about 25 times a minute during heavy exercise. Additionally, during exercise, we not only breathe faster but also breathe deeply so that we can take in more oxygen.

10.3 How do We Breathe

In general, we breathe in through the nostrils. The air passes from the nostrils to the nasal cavity and is then transferred to the lungs via windpipe. Lungs are present in the chest cavity on either side of the heart. The ribs surround them on all sides. The diaphragm, a big muscular sheet, makes the chest cavity floor. During inhalation, the ribs move outwards and up while the diaphragm goes down. Such movements create more space in the chest cavity, allowing the air to rush in and fill the lungs.

The opposite takes place during respiration. The ribs move inwards and downwards, and the diaphragm moves back to the original position. As a result, the space inside the chest cavity is decreased, and the air is gradually pushed out of the lungs.

Smoking causes damage to the lungs. It is also associated with cancer and should be avoided.

Air usually contains several unwanted particles like dust, smoke, and pollen, which irritate the nasal cavity. The hairs in the nostrils help to trap these irritants in the nose and prevent them from passing into the nasal cavity. However, when the irritants manage to pass to the nasal cavity, it stimulates sneezing. Sneezing is considered as a forced expulsion of dust and other irritants, thus ensuring only fresh air enters the nasal cavity. However, you should take care that you cover your nose while sneezing.

10.4 What do We Breathe Out

When we exhale, the exhaled air consists mainly of carbon dioxide. But it also contains water vapour and oxygen. That is why when we exhale air on a mirror, a film containing moisture forms on the mirror. Inhaled air consists of 21% oxygen and 0.04% carbon dioxide. Exhaled air consists of 16.4% oxygen and 4.4% carbon dioxide.

10.5 Breathing in Other Animals

Like human beings, other animals like cows, elephants, frogs, elephants, snakes, birds also breathe through lungs present in their chest cavities. However, some other organisms use different modes of respiration.  

Cockroach: Cockroaches have little openings on body sides called spiracles. Other insects have spiracles too. The spiracles are connected with the trachea, a number of the air tubes forming a network, which functions in gaseous exchange. Oxygen taken in by the spiracles gets diffused to the rest of the body through these tracheal tubes. Carbon dioxide is transferred from different cells in the tracheal tube in a similar manner and is exhaled out through the spiracles. Such a mode of respiration is present in insects only. 

Earthworms: The respiratory organs of an earthworm is skin. Their skin is slimy and moist and allows gas to pass through. A similar mode of respiration also takes place in frogs, although they have lungs like humans.

10.6 Breathing Under Water

Living organisms can also breathe in water. Fishes have gills to breathe in water. Gills are skin projections that have blood vessel supply and allow gaseous exchange.

10.7 Do Plants also Respire

Just like any other living organism on earth, plants carry out respiration. During respiration in plants, oxygen is taken in and carbon dioxide is given out. Oxygen is utilized in the breakdown of glucose in the cells and water and carbon dioxide are released. Every part of the plant body can take oxygen and release carbon dioxide. For example, leaves perform this exchange of gases through stomata. Roots get air from those air spaces present in the soil. That is why it is not recommended to over water any potted plant.

Exercise 10.7 total Solutions: 13 Questions (9 short questions and 4 Long questions).

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• A concise, pointwise representation of the CBSE class 7 science chapter 10 which helps the students to have a clear understanding of the subject. 

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• The questions included in this chapter cover the questions that are commonly asked from respiration in organisms class 7 chapter.

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