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Assertion (A): The rate of breathing in aquatic organisms is much slower than that seen in terrestrial organisms. Reason (R): The amount of oxygen dissolved in water is very low as compared to the amount of oxygen in air.(a) Both (A) and (R) are true and (R) is the correct explanation of (A).(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).(c) (A) is true, but (R) is false.(d) (A) is false, but (R) is true.

Question

Assertion (A): The rate of breathing in aquatic organisms is much slower than that seen in terrestrial organisms.
Reason (R): The amount of oxygen dissolved in water is very low as compared to the amount of oxygen in air.
(a) Both (A) and (R) are true and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).
(c) (A) is true, but (R) is false.
(d) (A) is false, but (R) is true.

June 26, 2025

Answer

(d) (A) is false, but (R) is true.

Explanation:

Assertion (A) is false: Aquatic organisms actually breathe faster, not slower, because oxygen is less available in water.
Reason (R) is true: Water contains much less dissolved oxygen than air.

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(a) Why is there a difference in the rate of breathing between aquatic organisms and terrestrial organisms? Explain. (b) Draw a diagram of the human respiratory system and label it – the pharynx, trachea, lungs, diaphragm and alveolar sac on it.

(a) Why is nutrition necessary for the human body? (CBSE 2020)
(b) What causes the movement of food inside the alimentary canal?
(c) Why is the small intestine in herbivores longer than in carnivores?
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(a) “Blood circulation in fishes is different from the blood circulation in human beings”. Justify the statement.
(b) Describe “blood circulation” in human beings.

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(b) The transport system in plants is slow.
(c) Circulation of blood in aquatic vertebrates differs from that in terrestrial vertebrates.
(d) During the daytime, water and minerals travel faster through the xylem as compared to the night.
(e) Veins have valves, whereas arteries do not.