What does demographics mean?

One function of the poly-a tail on eukaryotic mrna sequences is to the mrna be transported from the nucleus to the cytoplasm. prokaryotic mrna also has a poly-a tail. choose the best explanation of the prokaryotic poly-a tail. a. prokaryotic poly-a tails have the same functions as eukaryotic poly-a tails, because this process is highly conserved throughout different species. b. prokaryotic poly-a tails aren't important, because prokaryotes don't have nuclei. c. prokaryotic poly-a tails have other functions, because prokaryotes don't have nuclei. d. prokaryotic poly-a tails are composed of a different molecular structure compared with eukaryotic poly-a tails.

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important

Hector is back from his morning run and is feeling light-headed because his energy is depleted which food item will provide him with a quick source of carbohydrates