Assertion (A): The rate of breathing in aquatic organisms is much faster than in terrestrial organisms. Reason (R): The amount of oxygen dissolved in water is very high as compared to the amount of oxygen in air.

Chemical Reactions and Equations

Respiration and Oxidation

Options

(a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

(b)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

(c)Assertion (A) is true, but Reason (R) is false.

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

Official Answer

Assertion (A) is true, but Reason (R) is false.

dissolved oxygenlower concentrationbreathing rateaquatic organisms

Marking Scheme

11 mark for selecting option (c).

Hint

Think about the concentration of oxygen in water versus air. Does water have more oxygen than the atmosphere?

Quick Oral Answer

The rate of breathing is faster in aquatic organisms because the amount of dissolved oxygen in water is fairly low compared to the amount of oxygen in the air.

Analysis & Explanation

Assertion (A) is true because aquatic organisms need to extract oxygen from water. Since the concentration of dissolved oxygen in water is much lower than the concentration of oxygen in the atmosphere, aquatic organisms must breathe faster to meet their metabolic oxygen requirements. Reason (R) is false because the amount of dissolved oxygen in water is actually quite low (approx. 1%) compared to the 21% found in the air. Therefore, the reason provided is factually incorrect.

Common Mistakes

1Students often assume that because water is $H_2O$ , it has more oxygen available for breathing, but organisms rely on dissolved $O_2$ gas, not the oxygen atom in the water molecule.

Interesting Facts

While humans breathe about 12-20 times per minute, a fish's gill cover (operculum) movements are significantly more frequent to compensate for low oxygen levels.

Spotted a mistake or something unclear?

Tell us — we fix reported answers fast.

Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2024?

This question carries 1 mark in the CBSE Class 10 Science 2024 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Chemical Reactions and Equations" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Respiration and Oxidation" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2024 paper?

This is a MCQ question from Section A in the CBSE Class 10 Science 2024 paper.