1. The small microscopic units that make up organisms are called………………….

Cells

2. What is the smallest structural and functional unit of an organism?

Cell

3. Why do cells need energy?

Each cell in the body performs certain functions and for this purpose cells need energy.

4. Why do living organisms respire?

Living organisms respire to get the energy stored in food.

5. What is cellular respiration?

When organisms breathe in, the oxygen in the air reaches every cell in their body. In the cells, the oxygen helps to break down the food. This process of breakdown of food in the cells with the release of energy is called cellular respiration.

6. What is aerobic respiration?

During cellular respiration, oxygen breaks down glucose into carbon dioxide and water. When the breakdown of glucose occurs with the help of oxygen it is called aerobic respiration.

7. What is anaerobic respiration?

When food is broken down without using oxygen, it is called anaerobic respiration.

8. What are anaerobes?

Anaerobes are organisms that can survive in the absence of air. Example: yeast

9. What happens during aerobic respiration?

In the present of oxygen, glucose breaks down into carbon dioxide, water and energy.

10. What happens during anaerobic respiration?

In the absence of oxygen, glucose breaks down into alcohol, carbon dioxide and energy.

11. Why are yeasts used to make wine and beer?

Yeasts are anaerobes. That means they break down food without using oxygen. During this anaerobic respiration, glucose is broken down into alcohol and carbon dioxide. Hence, yeasts are used to make wine and beer.

12. Why do people get muscle cramps after heavy exercise?

During heavy exercise, our muscle cells respire anaerobically. When muscle cells break down glucose in the absence of oxygen, it leads to the production of lactic acid and energy. The accumulation of lactic acid in the muscle cells leads to cramps.

13. How does a massage or hot water bath give us relief from muscle cramps?

A hot water bath or massage improves the circulation of blood. As a result, the supply of oxygen to muscles increases. When muscle cells receive an adequate supply of oxygen, it results in the complete breakdown of lactic acid into carbon dioxide and water. As the accumulation of lactic acid is the cause of cramps, the breakdown of lactic acid into carbon dioxide and water will relieve the pain.

14. What is inhalation?

Inhalation is the process by which we take in air rich in oxygen into the body.

15. What is exhalation?

Exhalation is the process by which we give out air rich in carbon dioxide.

16. What is breathing rate?

Breathing rate is the number of times a person breathes in a minute.

17. Name the large muscular sheet which forms the floor of the chest cavity.

Diaphragm

18. What are spiracles?

These are the small openings on the sides of organisms like cockroaches.

19. How do cockroaches breathe?

Cockroaches has several small openings called spiracles on the sides of their body. Inside the body they have a network of air tubes called tracheae. When oxygen rich air enters the body through spiracles, they reach the tracheal tubes and diffuse into the body tissues. Thus, oxygen reaches every cell in the body. In the same way, carbon dioxide produced in the cells goes into the tracheal tubes and leaves the body through the spiracles.

20. Earth worms breathe through their ……………………..

Skin

21. …………………….. in fish help them to use oxygen dissolved in water.

Gills

22. What are the tiny pores present in the leaves that help with the exchange of oxygen and carbon dioxide?

Stomata

23. Name the respiratory organ in insects.

Trachea

24. What is the skeletal structure surrounding the chest cavity?

Rib cage

25. The respiratory organ of human beings

Lungs

26. The openings through which we inhale

Nostrils

Class 7 Science Solutions

• Class 7 Science Chapter 1 | Nutrition in plants | Important questions
• Class 7 Science Chapter 2 | Nutrition in animals | Expected Questions
• Class 7 Science Chapter 3 | Fibre to Fabric | Expected Questions
• Class 7 Science Chapter 4 | Heat | Expected Questions
• Class 7 Science Chapter 5 | Acids, Bases and Salts | One mark questions
• Class 7 Science Chapter 6 | Physical and Chemical Changes | Textbook solutions
• Class 7 Science Chapter 6 | Physical and Chemical Changes | Important Questions for Exam
• Class 7 Science Chapter 7 | Weather, Climate and Adaptations of Animals To climate | Textbook Solutions
• Class 7 Science Chapter 7 | Weather, Climate and Adaptations of Animals To Climate | Extra Questions
• Class 7 Science Chapter 8 | Wind, Storm and Cyclones Extra Questions
• Class 7 Science Chapter 9 | Soil | Extra questions
• Class 7 Science Chapter 10 | Respiration in Organisms | Textbook Solutions
• Class 7 Science Chapter 10 | Respiration in Organisms | Extra questions
• Class 7 Science Chapter 11 | Transportation In Animals And Plants | Important Questions
• Class 7 Science Chapter 12 | Reproduction in Plants | Important Questions
• Class 7 Science Chapter 13 | Motion and Time | Extra Questions
• Class 7 Science Chapter 14 | Electric Current And Its Effects | Important Questions