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Science · 2024 · 3 marks
CBSE 2024 · Region 1 · Set 1 · Q29
(i)Why is respiratory pigment needed in multicellular organisms with large body size ?(ii)Give reasons for the following :(a)Rings of cartilage are present in the throat.(b)Lungs always contain a residual volume of air.(c)The diaphragm flattens and ribs are lifted up when we breathe in.(d)Walls of alveoli contain an extensive network of blood vessels.
(i)
Why is respiratory pigment needed in multicellular organisms with large body size ?
(ii)
Give reasons for the following :
(a)
Rings of cartilage are present in the throat.
(b)
Lungs always contain a residual volume of air.
(c)
The diaphragm flattens and ribs are lifted up when we breathe in.
(d)
Walls of alveoli contain an extensive network of blood vessels.
Marking-scheme solution
(i) Diffusion /Diffusion pressure alone cannot take care of oxygen delivery to all parts of the body.
(ii) Reasons:
(a) To ensure that the air-passage does not collapse.
(b) There is sufficient time for oxygen to be absorbed and for the carbon dioxide to be released.
(c) Chest cavity becomes larger.
(d) Because exchange of gases takes place in the alveoli.
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CBSE Class 10 Science past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.