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Which of the following statement(s) is (are) true about the respiration?
(i) During inhalation, ribs move inward and diaphragm is raised.
(ii) In the alveoli, exchange of gases takes place i.e., oxygen from alveolar air diffuses into blood and carbon dioxide from blood into alveolar air.
(iii) Haemoglobin has greater affinity for carbon dioxide than oxygen.
(iv) Alveoli increases surface area for exchange of gases.

(A) (i) and (iv)
(B) (ii) and (iii)
(C) (i) and (iii)
(D) (ii) and (iv)

Last updated date: 17th Jun 2024
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Hint:Respiration is defined as the biochemical process wherein the living cells of an organism produces energy by taking in oxygen and liberating carbon dioxide from the oxidation of complex organic substances.

Complete answer:
Gas exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. Inhaled oxygen moves from the alveoli to the blood capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli.

During inhalation, the diaphragm contractions occur when they induce the lower ribs to move upward and forward, which also increases the thoracic volume. And the ribs move outward because of the central tendon of the diaphragm which pushes down the liver and stomach, and which acts like fulcrum.

Alveoli, is the site for gaseous exchange which increases the surface area for facilitating the process. And carbon monoxide has 210 times greater affinity for haemoglobin than oxygen .At the end of each bronchiole it is a special area that leads into a clump of tiny air sacs called alveoli.

Thus, the correct answer is option (D).

Note:The walls of alveoli share a membrane with the capillaries in which the oxygen and carbon dioxide move freely between the respiratory bloodstream. Oxygen molecules attach to red blood cells, which completely travel back to the heart. At the same time, the carbon dioxide molecules in the alveoli are blown out from the body with next exhalation.