Question

how do environmental factors alter gene expression?
alterations in dna methylation change which genes are accessible for expression.
environmental factors cause mutations in the dna.
changes in histone interaction with dna alters gene expression.
environmental factors determine which gene alleles are dominant or recessive.

Explanation:

Environmental factors often modify gene expression via epigenetic mechanisms. DNA methylation (option A) adds methyl groups to DNA, typically silencing genes by reducing accessibility to transcription machinery. Changes in histone interactions (option C) (e.g., acetylation, methylation) alter chromatin structure—loosening or tightening it to regulate gene accessibility. Mutations (option B) change DNA sequence, not just expression. Dominance/recessiveness (option D) is a genetic trait, not determined by environment. Thus, A and C are correct.

Answer:

A. Alterations in DNA methylation change which genes are accessible for expression.
C. Changes in histone interaction with DNA alters gene expression.