Assertion (A) : Human populations show a great deal of variations in traits. Reason (R) : All variations in a species have equal chances of surviving in the environment in which they live.

Q: Assertion (A) : Human populations show a great deal of variations in traits. Reason (R) : All variations in a species have equal chances of surviving in the environment in which they live.

The correct option is **(c)**. - **Assertion (A) is true** because human populations show a great deal of variation in traits (such as free or attached earlobes, height, eye color, etc.). - **Reason (R) is false** because not all variations in a species have equal chances of surviving in the environment. Survival depends on the nature of the variations and how advantageous they are in a given environment (e.g., bacteria that can withstand heat will survive better in a heat wave).

Heredity

Accumulation of Variation during Reproduction

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

The correct option is (c).

Assertion (A) is true because human populations show a great deal of variation in traits (such as free or attached earlobes, height, eye color, etc.).
Reason (R) is false because not all variations in a species have equal chances of surviving in the environment. Survival depends on the nature of the variations and how advantageous they are in a given environment (e.g., bacteria that can withstand heat will survive better in a heat wave).

variationsurvivalenvironmental factorsequal chances

Marking Scheme

11 mark for identifying that Assertion is true but Reason is false (option c).

Hint

Think about whether all variations, like sensitivity to heat in bacteria, have the same survival rate during a heat wave.

Quick Oral Answer

No, all variations do not have equal survival chances. Survival depends on the nature of the variation and environmental selection; for example, heat-resistant bacteria survive better in a heat wave.

Analysis & Explanation

The NCERT text explicitly states: 'human populations show a great deal of variation.' This makes Assertion (A) true. It also asks: 'Do all these variations in a species have equal chances of surviving in the environment in which they find themselves? Obviously not.' This makes Reason (R) false. Since the Assertion is true and the Reason is false, option (c) is the correct choice.

Common Mistakes

1Students often assume that all variations are beneficial and thus have equal survival chances, forgetting that environmental selection determines survival.

Interesting Facts

Some variations, like the ability of certain bacteria to withstand extreme heat, can save an entire population from extinction during environmental changes like heat waves.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2023?

This question carries 1 mark in the CBSE Class 10 Science 2023 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Heredity" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Accumulation of Variation during Reproduction" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2023 paper?

This is a MCQ question from Section A in the CBSE Class 10 Science 2023 paper.