Question

Why is endocytosis found in animals only?
A. This is only possible in animals where the plasma membrane is in direct contact with the external medium
B. Plants cells have a rigid cell wall as outermost covering
C. Both A and B
D. None of the above

Answer 1

Hint: The ability of endocytosis is directly related to the structure of the cell.

Complete answer:
Animal and plant cells are both eukaryotic cells and therefore the cell organelles like ribosomes, Golgi apparatus, etc are common to both of them. The major difference between them is the presence of a rigid cell wall in plant cells whereas no cell wall is present in animal cells. The cell membrane is fluid but the cell wall is a rigid structure. This is why endocytosis is found only in animal cells and not in plants.

Additional Information:
Two different types of bulk transport are seen in cells-
- Endocytosis: The inward transport of substances by employing a vesicle is called endocytosis. It is of two types, pinocytosis or cell drinking and phagocytosis or cell eating.
- Exocytosis: In this process substances, mostly waste materials are removed from the cells. It involves reverse pinocytosis.

Other methods of cellular transport are diffusion, facilitated diffusion, and active transport.

So, the correct answer is, Both A and B

Note: It should be remembered that even though plants cannot perform endocytosis, the exchange of materials does happen all the time. Plants cells have specialized connections known as plasmodesmata between adjacent cells which help in the transport of substances. These are cytoplasmic bridges.