Short pieces of RNA called micro RNAs play a role in cellular differentiation  acting in synchrony with protein transcription factors together the microRNAs protein transcription factors- A) prevent proteins that regulate gene expression within the cell from affecting the cell
B) destroy proteins that regulate gene expression within the cell
C) produce proteins that regulate gene expression within the cell
D) capture proteins outside the cell to regulate gene expression within the cell

parasites can detrimentally affect their host, but also must not allow their host to die before they can complete their life cycle. some parasites have complex life cycles with many different hosts, and have had to find ways of persisting in many different environments during the change from one host to another. ectoparasites live outside the body of the host, and can more easily  disperse, but are  more exposed to predators, parasites, parasitoids. endoparasites live inside the body of the host, and are therefore protected from the outside environment. but they can be  attacked by the host's immune system. they have therefore developed  mechanisms for dispersal such as  complex life cycles.

digestion

it excretes wastes