Q24
2 marksVery Short AnswerSection B

The survival of a species is promoted through creation of variations. Illustrate with an example.

How do Organisms Reproduce?
Importance of Variation
Official Answer

Variation is crucial for the survival of a species because environmental conditions (niches) can change drastically due to factors beyond the control of organisms, such as global temperature fluctuations, water level variations, or other ecological shifts. If a population of reproducing organisms is perfectly suited to a specific niche and that niche is drastically altered, the entire population could be wiped out. However, if variations are present in a few individuals, they might possess traits that allow them to survive the altered conditions, thereby ensuring the continuation of the species.


Example:

Consider a population of bacteria living in temperate waters. If the water temperature increases significantly due to global warming, most of these bacteria would die. However, a few variant bacteria that are resistant to heat would survive, reproduce, and grow further, preventing the species from going extinct.

variationsurvival of speciesnichetemperate watersbacteriaheat-resistantglobal warming

Marking Scheme

  • 11 mark
  • 21 mark

Hint

Think about how a sudden increase in water temperature affects a population of bacteria, and what allows some of them to survive.

Quick Oral Answer

Variation helps a species survive because if the environment changes drastically, some variant individuals with unique traits (like heat resistance in bacteria) can survive and keep the species from going extinct.

Analysis & Explanation

The NCERT text highlights that DNA copying during reproduction is not absolutely accurate, leading to variations. While these variations may not benefit an individual directly (and some drastic variations can even lead to cell death), they are highly beneficial to the species as a whole. In a changing environment, variation acts as an evolutionary buffer, ensuring that at least some individuals survive to propagate the species.

Common Mistakes

  1. 1Confusing the survival of an individual with the survival of a species. An individual variant might not have an immediate advantage, but the species benefits over time.
  2. 2Forgetting to mention the specific example of heat-resistant bacteria as requested by the prompt.

Interesting Facts

The built-in tendency for variation during DNA copying is the fundamental basis for organic evolution over generations.

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Frequently Asked Questions

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

This question carries 2 marks in the CBSE Class 10 Science 2024 examination.

Which chapter does this question come from in Science?

This question is from the chapter "How do Organisms Reproduce?" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Importance of Variation" from CBSE Class 10 Science.

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

This is a Very Short Answer question from Section B in the CBSE Class 10 Science 2024 paper.