Chapter 7, Problem 34A

Summary Introduction

To explain:

The difference and the relation between given terms.

Introduction : One of the main functions of cells is transport of substances. This is called cellular transport. There are different ways by which substances move in and out of the cell. These include osmosis, diffusion, active transport, endocytosis and exocytosis.

Answer to Problem 34A

Differences between endocytosis and exocytosis can be summarized in the following table:

Endocytosis	Exocytosis
1. It involves movement of large substances into a cell.	It involves movement of large substances out of the cell.
2. It involves movement of large molecules like proteins, complex sugars etc.	It helps in expelling wastes and substances like hormones.

Both endocytosis and exocytosis are methods of cellular transport that help in transport of large molecules.

Explanation of Solution

Endocytosis: It is a process by which a cell surrounds a substance in the outside environment, encloses the substance in a portion of the plasma membrane. The plasma membrane then pinches off and leaves the substance inside the cell in a vacuole.

Exocytosis: It involves secretion of materials at the plasma membrane. It is reverse of endocytosis. Cells use this method to expel wastes and to secrete substances such as hormones.

Both these methods help in transport of substances and wastes into and out of the cell. Endocytosis and exocytosis both require input of energy.