4

Set 3: Central Ideas (Advanced)

Explanation

Answer: D

PASSAGE

The following text discusses Epigenetics. Epigenetics is the study of heritable changes in gene expression (active versus inactive genes) that do not involve changes to the underlying DNA sequence. Mechanisms such as DNA methylation can 'tag' DNA, effectively silencing or activating genes in response to environmental factors like diet, stress, or pollutant exposure. This field has revolutionized biology by showing that one's genetic destiny is not fixed at birth; rather, the genome is dynamic and responsive to lived experience.

How does epigenetics challenge the traditional view of genetics?

A. By proving that DNA sequences change rapidly
B. By showing that gene expression can change without altering the DNA sequence
C. By demonstrating that environment has no effect on biology
D. By replacing DNA with RNA as the primary hereditary molecule✓ Correct

Detailed Explanation

Choice B is correct. The text defines it as 'changes in gene expression... that do not involve changes to the underlying DNA sequence.'

Key Evidence:

• "do not involve changes to the underlying DNA sequence"

• "genome is dynamic and responsive"

Why others are wrong: A (Opposite (DNA sequence doesn't change)), C (Opposite (Shows environment DOES effect expression)), D (Inaccurate).

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