General Science 7th Class Chapter 2 Human Respiratory and Circulatory Systems Solved Exercise

General Science

7th Class

Chapter 2

Human Respiratory and Circulatory Systems

Questions

2.1 Encircle the correct option.

1. Exchange of gases takes place in:

a. lungs        b. bronchioles        c. alveoli        d. blood

2. Trachea divides into two:

a. bronchi        b. veins        c. villi        d. ribs

3. The part of the heart which receives blood from lungs:

a. left atrium        b. right atrium        c. left ventricle        d. right ventricle

4. Left atrium opens into:

a. Right atrium        b. right ventricle        c. left ventricle        d. aorta

5. Right atrium receives:

a. oxygenated blood        b. deoxygenated blood        c. both types of blood        d. no blood

6. Blood vessels that carry blood away from the heart are:

a. capillaries        b. veins        c. arteries        d. venules

7. Aerobic respiration takes place in:

a. mitochondria        b. chloroplasts        c. nucleus        d. blood vessels

8. Products of anaerobic respiration in yeasts are _________ along with energy:

a. carbon dioxide and water        b. ethanol and carbon dioxide

c. oxygen and water        d. lactic acid and water

9. Exchange of material in the body tissues and blood takes place in:

a. aorta        b. ventricles        c. veins        d. capillaries

10. Which of the following plays an important role in blood clotting?

a. red blood cells        b. white blood cells        c. platelets        d. bone cells

2.2 Differentiate between:

1. Aerobic and anaerobic respiration

Ans:

Aerobic Respiration:

• It takes place in the presence of oxygen
• Large amount of energy is released in aerobic respiration
• Carbon dioxide and water are the products of aerobic respiration

Anaerobic Respiration:

• It takes place in the absence of oxygen
• Small amount of energy is released in anaerobic respiration
• Lactic acid is produced in muscle. Ethanol and carbon dioxide are produced in yeast

2. Oxygen and carbon dioxide

Ans:

Oxygen:

     In animals, oxygen is very important for the process of aerobic respiration. In result,             large amount of energy is released in organism's body. Organisms inhale oxygen from         environment.

Carbon dioxide:

     Carbon dioxide is the by product of respiration and it is exhaled from lungs by animals         and in plants by stomata.

3. Breathing and respiration

Ans:

Breathing:

• Breathing is the exchange of gases by inhalation and exhalation of the air.
• It takes place in alveoli of the lungs.
• The purpose of breathing is to provide oxygen to all the body cells and getting rid of carbon dioxide produced in the cells.

Respiration:

• Respiration is a process to release energy from food during a series of reaction, each of which is catalyzed by specific enzymes.
• It takes place in mitochondria of the cells.
• The purpose of respiration is to provide energy to the whole body for carrying on the activities of life.

4. Arteries and Veins

Ans:

Arteries:

• Carry blood away from the heart
• Thick walled vessels
• Facing high blood pressure
• having no valves
• Carry blood having oxygen and nutrients for the body cells, except pulmonary artery which carries deoxygenated blood.

Veins:

• Carry blood towards the heart
• Thin walled vessels
• Facing low blood pressure
• Veins have valves
• Return blood carrying carbon dioxide and other wastes, except pulmonary vein which carries oxygenated blood.

5. Capillaries and alveoli

Ans:

Capillaries:

    Capillaries provide surface area for exchange of materials between the body cells and blood cells.        They provide oxygen and nutrients to the cells and collect carbon dioxide and other wastes from the     cells.

Alveoli:

    In lungs, each bronchiole ends in a group of air sacs or alveoli. The lungs look like sponges due to        the presence of alveoli. Millions of alveoli are found in the lungs. They are surrounded by thick            network of blood capillaries.

2.3 Give short answers.

i. Name the body parts involved in breathing system.

Ans.

1. Nose or Mouth

2. Trachea

3. Bronchus

4. Bronchiole

5. Alveolus in lung

6. Blood Capillaries

ii. Name the products of anaerobic respiration which occurs in muscles.

Ans.

Lactic acid is the product of anaerobic respiration which occurs in muscle.

iii. Name different blood cells.

Ans.

(i) Red blood cells (RBCs)

(ii) White blood cells (WBCs)

(iii) Platelets

iv. Where does blood oxygenate?

Ans.

Blood is oxygenated by alveoli in the lungs.

v. Name different chambers of human heart.

Ans.

Human Heart has following chambers:

1. Right atria

2. Left atria

3. Right ventricle

4. Left ventricle