Chapter 7, Problem 37A

Summary Introduction

Introduction :

Molecules can move into or out of cells by a different type of transportation method which primarily depends on the concentration gradient.

Transportation across cell membrane takes place by two methods: Passive transport and Active transport.

Answer to Problem 37A

Correct answer :

The correct answer is option (A) active transport.

Explanation of Solution

Explanation/justification for the correct answer :

Option (A) is Active Transport.It is the movement of molecules across the cell membrane by using cellular energy. In this process,molecules movefrom their lower concentration to higher concentration through the plasma membrane. Molecules move against the concentration gradient,and to do soenergy is required. Hence, this option is correct.

Explanation for incorrect answer :

Option (B) Facilitated diffusion: This is the process of diffusion of molecules across the plasma membrane through transport protein or carrier protein. Molecules move down the concentration gradient and hence energy is not required to do so.Hence, this option is incorrect.

Option (C) Osmosis: It is the process in which water molecules move from their higher concentration to their lower concentration. This process is also known as diffusion of water molecules and energy is not required.Hence, this option is incorrect.

Option (D) Simple diffusion: It is the process in which ions or molecules move from their higher concentration to their lower concentration and hence energy is not required.Hence, this option is incorrect.