Question

why endocytosis is present in only animals?

Answer 1

Endocytosis is engulfment of food and other substances from external medium by plasma membrane. This is possible only when plasma membrane is in direct contact with external medium. It occurs only in animal cells. In plant cells, a cell wall is present over the plasma membrane. Therefore, their plasma membranes cannot perform endocytosis

Answer 2

Endocytosis generally occurs in animal cells and very rarely in plant cells as the cell membrane in plant cell is surrounded by a rigid cell wall. Cell wall causes hindrance in the invagination of plasma membrane which forms the transport vesicles for the transfer of substances in the cytoplasm of the cell. 

Nitrogen fixing bacteria enter the root cells in legumes through endocytosis