Textbook Solution: Respiration in Living Beings | Class 7 Oxford Science: Chapter Notes, Worksheets & Tests PDF Download

A. Choose the correct option.

1.
Ans: (a)

2.
Ans: (b)

3.
Ans: (d)

4.
Ans: (b)

5.
Ans: (c)

B. Fill in the blanks with the correct words.

1.
Ans: Carbon dioxide and water are formed as waste products of aerobic respiration.

2
Ans: Insects breathe through holes called spiracles.

3.
Ans: Aquatic animals breathe with the help of gills.

4.
Ans: Exchange of gases in plants occurs in the stomata.

5.
Ans: Carbon dioxide and alcohol are products of anaerobic respiration.

C. Name the following

1.
Ans: The process that releases energy from the breakdown of food is called Respiration.

2.
Ans: The process that involves taking in oxygen-rich air and giving out carbon dioxide-rich air is called Breathing.

3.
Ans: Animals that are made up of a single cell are called Unicellular animals.

4.
Ans: Thin blood vessels that form a network around alveoli are called Capillaries.

5.
Ans: Breathing organ of a fish is called Gills.

D. Write T for true and F for false.

1.
Ans: The diaphragm is indeed a dome-shaped muscle that is present beneath the lungs, not above them. It helps in the process of inhalation and exhalation by contracting and relaxing, respectively. - True

2.
Ans: The exchange of gases in human beings occurs in the alveoli. This is where oxygen is absorbed into the bloodstream and carbon dioxide is expelled from the body. - True

3.
Ans: Aerobic respiration occurs in the presence of oxygen, not its absence. It is the process by which energy is produced from food in the presence of oxygen. - False

4.
Ans: Most plants and animals, including human beings, do carry out aerobic respiration. This is a process that requires oxygen to produce energy. - True

5.
Ans: Spiracles are the sites for the exchange of gases in insects, not in plants. In plants, gas exchange occurs through tiny holes on the underside of their leaves called stomata. - True

E. Answer the following questions.

1.
Ans: Respiration is the process by which oxygen is used to break down food to release energy. Living things need to respire to produce energy which is required for all bodily functions and activities.

2.
Ans: Breathing is the process by which oxygen-rich air is taken into the body and carbon dioxide-rich air is removed from the body. It involves two processes: inhalation and exhalation. Respiration, on the other hand, is the process by which the inhaled oxygen is used to break down food to release energy.

3.
Ans: Unicellular animals, which are made up of a single cell, respire by taking up and releasing air directly from their surroundings through the simple process of diffusion. They do not have special organs for exchange of gases.

4.
Ans: Fish breathe in water through special organs called gills. These gills absorb oxygen from the water as it passes over them. The oxygen is then transported by the blood to all parts of the fish's body. Carbon dioxide, a waste product, diffuses into the outgoing water.

5.
Ans: Frogs are amphibians which means they can breathe both on land and in water. On land, frogs breathe through their lungs. When in water, frogs, as well as some other amphibians, can respire through their moist skin.

6.
Ans: The diaphragm, a dome-shaped muscle beneath the lungs, plays a crucial role in breathing. During inhalation, the diaphragm contracts (moves downwards) to allow air into the lungs where oxygen is absorbed by the blood. During exhalation, the diaphragm relaxes (moves upwards) and carbon dioxide-rich air is pushed out of the lungs.

7.
Ans: Root respiration refers to the process where the roots of plants take in oxygen from the air trapped within soil particles, and give off carbon dioxide. This process is important as it provides the necessary oxygen for the roots to function and grow.

8.
Ans: Gills are special organs that help aquatic animals to breathe. They are richly supplied with blood from blood vessels called capillaries. When water passes over the gills, oxygen is absorbed from the water into the blood, and is transported to all parts of the animal's body. At the same time, carbon dioxide diffuses into the outgoing water.

9.
Ans: Aerobic respiration refers to the type of respiration that requires oxygen for producing energy. This process results in the complete breakdown of carbohydrates, producing a large amount of energy, water, and carbon dioxide. On the other hand, anaerobic respiration occurs without oxygen and results in the incomplete breakdown of carbohydrates, producing lesser energy, and forming carbon dioxide and alcohol as byproducts.