Question 1

Which of the following best explains why cells are limited in size by their surface area-to-volume ratio?

Accepted Answer

As cells grow, their volume increases faster than their surface area, reducing the efficiency of material exchange.

Question 2

A 4-mm cube cell has a surface area of $$96\ \mathrm{mm}^2$$ and a volume of $$64\ \mathrm{mm}^3. $$What is its surface area-to-volume ratio?

Accepted Answer

$$1.5:1$$

Question 3

Which component of the plasma membrane is primarily responsible for its selective permeability?

Accepted Answer

Phospholipid bilayer

Question 4

Which of the following best describes the role of cholesterol in the plasma membrane?

Accepted Answer

It helps to increase membrane fluidity and stability.

Question 5

A cell is placed in a solution and water moves into the cell. What is the tonicity of the solution relative to the cell?

Accepted Answer

Hypotonic

Question 6

Which of the following transport processes requires energy in the form of ATP?

Accepted Answer

Primary active transport

Question 7

Which of the following is NOT a type of passive transport?

Accepted Answer

Primary active transport

Question 8

Which membrane protein is directly involved in facilitated diffusion?

Accepted Answer

Both channel and carrier proteins

Question 9

A patient is given an intravenous solution that is hypertonic to their red blood cells. What will happen to the cells?

Accepted Answer

They will lose water and shrink.

Question 10

Which of the following best describes the process of diffusion?

Accepted Answer

Movement of molecules from an area of higher concentration to an area of lower concentration.

Question 11

Which of the following scenarios is an example of co-transport (secondary active transport)?

Accepted Answer

Glucose is transported into a cell along with sodium ions, using the sodium gradient established by the sodium-potassium pump.

Question 12

Which of the following statements about integral proteins is correct?

Accepted Answer

They span the membrane and have both hydrophobic and hydrophilic regions.

Question 13

Which of the following best describes osmosis?

Accepted Answer

The diffusion of free water across a selectively permeable membrane.

Question 14

Which of the following factors does NOT affect the rate of diffusion across a membrane?

Accepted Answer

The color of the solute

Question 15

A cell with a high surface area-to-volume ratio is most likely to:

Accepted Answer

Efficiently exchange materials with its environment.

Question 16

Which of the following is a function of glycoproteins in the plasma membrane?

Accepted Answer

Cell recognition and signaling

Question 17

Which process is illustrated by the movement of sugar molecules from a lump into water until evenly distributed?

Accepted Answer

Diffusion

Question 18

Which of the following best describes the movement of oxygen across the plasma membrane?

Accepted Answer

Simple diffusion through the phospholipid bilayer

Question 19

Which of the following is true about peripheral proteins?

Accepted Answer

They are not embedded in the membrane and interact with integral proteins or phospholipid heads.

Question 20

Which of the following best explains why facilitated diffusion is necessary for some molecules?

Accepted Answer

Some molecules are too large or polar to pass through the lipid bilayer directly.

Membrane Structure and Transport: Surface Area, Fluidity, and Permeability

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