Question 1

Which component of the fluid mosaic model is primarily responsible for the selective permeability of cellular membranes?

Accepted Answer

Phospholipid bilayer

Question 2

A red blood cell is placed in a hypotonic solution. What will most likely happen to the cell, and which physical principle explains this?

Accepted Answer

It will swell and possibly burst due to osmosis, where water moves from low solute concentration to high solute concentration.

Question 3

Which type of membrane protein is covalently attached to fatty acids and is embedded within the membrane but does not span it?

Accepted Answer

Lipid-anchored protein

Question 4

Which equation best describes the net movement of solute during simple diffusion across a membrane?

Accepted Answer

$$J = -D \frac{dC}{dx}$$

Question 5

Which of the following is NOT a function of cellular membranes as listed in Table 5.1?

Accepted Answer

Synthesis of DNA

Question 6

A mutation causes the loss of cadherin proteins in epithelial cells. Which cellular process would be most directly affected?

Accepted Answer

Cell adhesion and recognition

Question 7

Which type of junction allows ions and small molecules to pass directly from one animal cell to another?

Accepted Answer

Gap junction

Question 8

Which process requires energy input and moves substances against their concentration gradient?

Accepted Answer

Primary active transport

Question 9

A glucose molecule enters a cell via a transporter that does not require ATP but does require a protein. What type of transport is this?

Accepted Answer

Facilitated diffusion

Question 10

Which of the following best describes the role of integrins in cellular membranes?

Accepted Answer

They connect cells to the extracellular matrix and transmit signals.

Question 11

Which of the following is a real-world example of receptor-mediated endocytosis?

Accepted Answer

Uptake of low-density lipoprotein (LDL) cholesterol into liver cells

Question 12

Which structural protein in the extracellular matrix provides tensile strength to animal tissues?

Accepted Answer

Collagen

Question 13

Which of the following statements about the permeability of the phospholipid bilayer is correct?

Accepted Answer

Small nonpolar molecules pass through easily, while ions and large polar molecules require transport proteins.

Question 14

Which equation represents the energy required to move an ion across a membrane against its electrochemical gradient?

Accepted Answer

$$\Delta G = RT \ln \left( \frac{[C]_2}{[C]_1} \right) + zF\Delta \Psi$$

Question 15

Which of the following is a function of ion gradients across cellular membranes?

Accepted Answer

Regulation of cytosolic pH

Question 16

A nerve cell uses the Na+/K+-ATPase to maintain high intracellular K+ and low intracellular Na+. What type of transport is this, and what is the energy source?

Accepted Answer

Primary active transport; ATP hydrolysis

Question 17

Which plant cell junction allows direct cytoplasmic exchange between adjacent cells?

Accepted Answer

Plasmodesmata

Question 18

Which process is responsible for the secretion of insulin from pancreatic cells into the bloodstream?

Accepted Answer

Exocytosis

Question 19

Which of the following best explains why animal cells do not burst in hypotonic environments, while plant cells maintain turgor pressure?

Accepted Answer

Animal cells actively pump water out, while plant cells have a rigid cell wall.

Question 20

Which of the following is a correct description of a symport transporter?

Accepted Answer

It moves two substances in the same direction across the membrane.

Cellular Membranes: Structure, Function, and Transport

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