Why is it important for a cell to be able to turn a gene off?

Which animal group is the largest and contains more species from all the other living groups combined? is it mammals or

Write a paragraph at least 5 sentences “why all vaccinations should be mandatory”

The nervous system interacts with the endocrine system by a. using hormones as connections b. sending nerve impulses directly to glands c. using neuroendocrine cells as connections d. sending neurotransmitters directly to neurons