In the Arctic, seals are one of the main sources of food for polar bears. As global warming melts polar ice, fewer seals can be found in the Arctic. As a result, polar bears will — A. maintain a constant population.

B. decrease in number.

C. migrate to tropical regions.

D. increase in number.

Decrease in numbers, because of their lack of a food source.

phylogenetic tree is the tree of life or evolution tree. it shows the different branches of evolution. the sequence goes like tissues - coelom - backbone - endoskeleton - segmentation

a scenario where a cell may be needed to perform a form of endocytosis is when transporting large molecules. a scenario where a cell may be needed to perform a form of exocytosis is when releasing the large molecule from the cell.