How does histone acetylation affect chromatin?

a) it loosens the chromatin and allows increased transcription.
b) it allows dna to become resistant to damage.
c) it the histones have a greater affinity for dna.
d) it inhibits dna replication by making it more difficult to separate the dna strands.
e) it causes the chromatin to become more condensed in preparation for metaphase.

The correct answer is option A.

Explanation:

The histone acetylation catalyzed by histone acetyltransferases and deacetylation catalyzed by histone deacetylases performs a significant role in the regulation of the expression of genes in eukaryotes. Histone acetylation diminishes the affinity of histones towards DNA leading to relaxing or decondensation of chromatin and becomes accessible to the transcriptional apparatus and to perform transcription.  

It can be stated that histone acetylation is related to expression or gene or activation and histone deacetylation is related to the inactivation of gene or repression.  

d concave shape of wave rock

explanation:

the concave shape of wave rock is a very good evidence that supports the evolution of earth due to chemical weathering. if we talk about structure of   wave rock, studies have estimated that it is around 2.7 billion years old. it also serves as the foundation of evidence that it was the place where australian continent began to form.

how the structure of wave rock was created?

studies suggest that structure of wave rock was created when the surrounded area was started to weather due to which deposition of material started on the part of land which now contains wave rock.

the structure of wave rock is considered to be one of the best-known landforms in australia. at the height of around 15 cm, there can be found flared slopes which formulate the margins of hyden rock. it is now assumed by geologists that wave rock was created by subsurface water-induced weathering and not by glaciers, waves or wind.

due to deposition of material over the period of long time, the wave rock became tougher and tougher due to weathering from surrounding terrain. this makes it a physical evidence that supports   the evolution of earth due to chemical weathering.

hope it !