NCERT Class 11-Biology: Chapter –17 Breathing and Exchange of Gases Part 4

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Short Answer Type Questions

Question 1:

State the different modes of transport in blood.

Answer:

Around of the is transported via blood and the remaining of it is transported via plasma. The three main ways by which is transported in blood are:

1. In Red blood cells carbon dioxide combines with water and forms carbonic acid. It is an unstable form and gets disassociated into hydrogen and bicarbonate ion.

2. Carbon dioxide is also transported through plasma in the form of bicarbonate ions.

Question 2:

Compared to , diffusion rate of through the diffusion membrane per unit difference in partial pressure is much higher. Explain.

Answer:

Diffusion rate of any gas depends upon the solubility rate of the gas. Diffusion rate is directly proportional to the solubility rate. As the solubility of Carbon dioxide is much higher than oxygen it’s diffusion rate through the diffusion membrane per unit difference in partial pressure is much higher.

Question 3:

For completion of respiration process, write the given steps in sequential manner

a. Diffusion of gases across alveolar membrane.

b. Transport of gases by blood.

c. Utilisation of by the cells for catabolic reactions and resultant release of .

d. Pulmonary ventilation by which atmospheric air is drawn in and rich alveolar air is released out.

e. Diffusion of and between blood and tissues.

Answer:

The correct sequence would be:

1. Pulmonary ventilation by which atmospheric air is drawn in and CO2 rich alveolar air is released out.

2. Diffusion of gases across alveolar membrane.

3. Transport of gases by blood.

4. Diffusion of between blood and tissues.

5. Utilisation of O2 by the cells for catabolic reactions and resultant release of .

So, the correct sequence would be d, a , b, e and c.

Question 4:

Differentiate between

a. Inspiratory and expiratory reserve volume

b. Vital capacity and total lung capacity

c. Emphysema and occupational respiratory disorder

Answer:

(a) Additional volume of air a person can inspire by a forcible inspiration is called inspiratory reserve volume (IRV.) Additional volume of air a person can expire by a forced expiration is called expiratory reserve volume (ERV). In a normal individual, IRV is about while is about

(b) The maximum volume of air person can breathe in after a forced expiration, or the maximum volume of air a person can breathe out after a forced inspiration is called Vital Capacity. The total volume of air in lungs at the end of a forced inspiration is called total lung Capacity

(c) Alveoli walls are damaged in emphysema, while any other part of the respiratory system could be damaged in occupational respiratory disorder. Smoking is a major cause of emphysema. Fine particles generated during some mechanical processes are the cause of occupational respiratory disorder.

Long Answer Type Questions

Question 1:

Explain the transport of and between alveoli and tissue with diagram.

Answer:

Transportation of oxygen:

1. When oxygen is inhaled it reaches the alveoli (tiny balloon like structures which are in close proximity of various thin capillaries).

2. Now, the partial pressure of oxygen is more in the alveoli than the capillaries .

3. This causes the diffusion of oxygen into the capillaries

4. After which oxygen combines with Haemoglobin to form oxyhaemogl

5. This oxygenated blood reaches the organs which have low partial pressure than the capillaries.

6. In these organs the bond between oxygen and haemoglobin becomes unstable and breaks releasing oxygen into the organs.

Transportation of Carbon Dioxide:

Carbon dioxide is transported by three different methods which are:

3. Blood carries released carbon dioxide from various organs to the alveoli via capillaries which have lower intra pulmonary pressure than the organs.

4. Now, carbon dioxide is then diffused into the alveoli from the capillaries due to lower intra pulmonary pressure in the alveoli than the capillaries

5. In Red blood cells carbon dioxide combines with water and forms carbonic acid. It is an unstable form and gets disassociated into hydrogen and bicarbonate ion.

6. Carbon dioxide is also transported through plasma in the form of bicarbonate ions.

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