Modifications of histone tails can: affect expression of some genes in response to the environment. affect chromatin structure. activate transcription of some genes. repress transcription of some genes. all of these choices are correct.

All of these choices are correct.

Explanation:

Histone modification can be defined as a type of gene expression regulation. It refers to covalent post-translational modifications of histon tail proteins such as methylation, phosphorylation, acetylation, ubiquitylation, and sumoylation. As a consequence of modifications, chromatin structure might be changed, into active regions of euchromatin, (active transcription), or heterochromatin regions (inactive transcription).

Modification might be due to response to the environment, are heritable and are called epigenetic control.

the answer is 1. photosynthesis. glad to

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

i hope this : )