Cell Membrane and Transport Quiz

What is the primary function of the cell membrane in cellular transport?

• To produce energy for the cell

• To regulate the movement of substances in and out of the cell

• To store genetic information

• To synthesize proteins

Answer explanation

The primary function of the cell membrane is to regulate the movement of substances in and out of the cell, maintaining homeostasis and allowing selective permeability, which is crucial for cellular function.

Tags

VA.BIO.3.d.

Which of the following best describes the structure of the cell membrane?

• A rigid layer of cellulose

• A double layer of phospholipids with embedded proteins

• A single layer of lipids

• A thick layer of proteins

Answer explanation

The cell membrane is best described as a double layer of phospholipids with embedded proteins, known as the fluid mosaic model. This structure allows for flexibility and the movement of substances in and out of the cell.

Tags

VA.BIO.3.d.

How does the cell membrane maintain homeostasis within the cell?

• By allowing all substances to pass freely

• By selectively allowing certain substances to pass while blocking others

• By producing enzymes for digestion

• By storing excess nutrients

Answer explanation

The cell membrane maintains homeostasis by selectively allowing certain substances to pass while blocking others. This selective permeability ensures that essential nutrients enter the cell while waste products are kept out.

Tags

VA.BIO.3.d.

Which of the following processes involves the movement of water across the cell membrane?

• Active transport

• Osmosis

• Endocytosis

• Exocytosis

Answer explanation

Osmosis is the process that specifically involves the movement of water across a cell membrane, driven by concentration gradients. Active transport, endocytosis, and exocytosis involve different substances or mechanisms.

Tags

VA.BIO.3.d.

What role do proteins play in the cell membrane?

• They provide energy for the cell

• They act as channels and carriers for molecules

• They store genetic information

• They form a rigid structure

Answer explanation

Proteins in the cell membrane serve as channels and carriers, facilitating the transport of molecules in and out of the cell, which is essential for maintaining cellular function and homeostasis.

Tags

VA.BIO.3.d.

Which of the following is a characteristic of passive transport across the cell membrane?

• It requires energy in the form of ATP

• It moves substances against their concentration gradient

• It involves the movement of substances down their concentration gradient

• It is only used for large molecules

Answer explanation

Passive transport involves the movement of substances down their concentration gradient, meaning they move from areas of higher concentration to lower concentration without the use of energy.

Tags

VA.BIO.3.d.

What is the function of cholesterol in the cell membrane?

• To provide energy for transport

• To stabilize the membrane's fluidity

• To act as a channel for ions

• To store genetic material

Answer explanation

Cholesterol plays a crucial role in stabilizing the fluidity of the cell membrane. It helps maintain membrane integrity by preventing it from becoming too rigid or too fluid, ensuring proper function.

Tags

VA.BIO.3.d.

Which type of transport requires energy to move substances across the cell membrane?

• Diffusion

• Facilitated diffusion

• Active transport

• Osmosis

Answer explanation

Active transport requires energy to move substances against their concentration gradient, while diffusion, facilitated diffusion, and osmosis occur passively without energy input.

Tags

VA.BIO.3.d.

What is the role of glycoproteins in the cell membrane?

• To provide structural support

• To facilitate cell-cell recognition and communication

• To transport water molecules

• To synthesize lipids

Answer explanation

Glycoproteins play a crucial role in facilitating cell-cell recognition and communication by serving as markers on the cell surface, allowing cells to identify and interact with each other.

Tags

VA.BIO.3.d.

Which of the following statements about the cell membrane is true?

• It is impermeable to all substances

• It is composed entirely of proteins

• It is selectively permeable, allowing some substances to pass while blocking others

• It is a single-layered structure

Answer explanation

The cell membrane is selectively permeable, meaning it allows certain substances to pass through while blocking others. This property is essential for maintaining homeostasis in the cell.

Tags

VA.BIO.3.d.