Chapter 8 Cell Transport Introduction

What is the main function of the cell membrane?

• To regulate what enters and leaves the cell

• To produce energy

• To store genetic information

• To synthesize proteins.

Answer explanation

The main function of the cell membrane is to regulate what enters and leaves the cell, maintaining homeostasis and protecting the cell's internal environment.

The cell membrane provides _______ and support to the cell.

• A) energy

• B) protection

• C) genetic material

• D) enzymes

Answer explanation

The cell membrane acts as a barrier, providing protection and support to the cell by regulating what enters and exits, thus maintaining the cell's integrity. Therefore, the correct answer is B) protection.

What is the main structural component of cell membranes?

• Carbohydrates

• Phospholipids

• Nucleic acids

• Sugars

Answer explanation

The main structural component of cell membranes is phospholipids. They form a bilayer that provides a barrier and fluidity, allowing for the selective permeability of the membrane, unlike carbohydrates, nucleic acids, or sugars.

The cell membrane consists of a _______ bilayer in which proteins are embedded.

• carbohydrate

• phospholipid

• nucleic acid

• sugar

Answer explanation

The cell membrane is primarily composed of a phospholipid bilayer, which provides structure and fluidity, allowing proteins to be embedded within it. This is essential for various cellular functions.

Which type of protein forms channels and pumps to help move materials across the cell membrane?

• Receptor proteins

• Transport proteins

• Enzymes

Answer explanation

Transport proteins are specialized proteins that form channels and pumps in the cell membrane, facilitating the movement of materials in and out of the cell. This makes them essential for cellular transport.

Receptor proteins recognize and bind to substances at the cell surface, forming a method of _______ between the cell and the external environment.

• digestion

• communication

• transportation

Answer explanation

Receptor proteins facilitate communication by recognizing and binding to substances, allowing cells to interact with their external environment effectively.

What is the function of carbohydrates in the cell membrane?

• Energy storage

• Identification markers

• Structural support

• Transport of molecules

Answer explanation

Carbohydrates in the cell membrane serve as identification markers, allowing cells to recognize and communicate with each other. They play a crucial role in cell signaling and immune response.

Carbohydrates in the cell membrane serve as ______ to help individual cells identify one another.

• energy sources

• identification markers

• structural components

• transport channels

Answer explanation

Carbohydrates in the cell membrane act as identification markers, allowing cells to recognize and communicate with each other. This is crucial for processes like immune response and tissue formation.

What does the term 'fluid mosaic' describe in cell membranes?

• The rigid structure of membranes

• The static nature of membranes

• The dynamic and flexible nature of membranes

• The solid nature of membranes.

Answer explanation

The term 'fluid mosaic' describes the dynamic and flexible nature of cell membranes, highlighting that they are not rigid or static, but rather consist of various components that move and interact freely.

The phospholipid bilayer acts more like a ______ than a solid.

• gas

• liquid

• crystal

• gel

Answer explanation

The phospholipid bilayer is fluid in nature, allowing for movement and flexibility, similar to a liquid. This property is essential for cell membrane function, making 'liquid' the correct choice over the other options.