Question

what type of experience can alter gene expression?
wartime trauma
all of the answers
high levels of stress
exposure to pollution
question 6
how does dna methylation block transcription?
by preventing the dna from wrapping around the histones
by preventing the chromatins from unwinding

Explanation:

1. Wartime trauma, high stress, and pollution exposure are all environmental/experiential factors that can induce epigenetic changes altering gene expression, so all options are correct.
2. DNA methylation typically leads to tighter chromatin packing, which prevents chromatin from unwinding and accessing transcription machinery, thus blocking transcription; preventing DNA from wrapping around histones would have the opposite effect of loosening chromatin.

Answer:

1. All of the answers
2. By preventing the chromatins from unwinding