How can plants and animals affect neighboring cells directly?

Plants and animals affect neighboring cells directly because when in terms with the plants, they use their plasmodesmata in which allowed them to communicate and affect neighboring cells. While the animals use their gap junctions that is use for them to communicate and affect their neighboring cells.

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.

the endomembrane system i think