Q: A cell is placed in a solution containing a high concentration of Na\textsuperscript{+}. Which membrane protein is most likely to be involved in maintaining the cell's internal environment?

Na\textsuperscript{+}/K\textsuperscript{+} ATPase pump

Q: Which of the following is a multi-step process involving both direct and indirect active transport in a cell?

Coupled transport where Na\textsuperscript{+} gradient created by ATPase is used to drive glucose uptake via a symporter

Question 1

Which of the following best explains why biological membranes act as effective permeability barriers?

Accepted Answer

Their interior is hydrophobic, preventing the free passage of most polar molecules.

Question 2

A researcher observes that a membrane protein can be removed from the membrane by changing the pH or ionic strength of the solution. What type of membrane protein is this most likely to be?

Accepted Answer

Peripheral membrane protein

Question 3

Which of the following statements about the fluid mosaic model of membrane structure is correct?

Accepted Answer

Lipids and proteins can move laterally within the membrane, creating a dynamic structure.

Question 4

Which class of membrane lipids is primarily responsible for the amphipathic nature of biological membranes?

Accepted Answer

Phospholipids

Question 5

A cell membrane contains a high proportion of cis-unsaturated fatty acid tails. What effect does this have on membrane fluidity?

Accepted Answer

It increases fluidity by introducing kinks that prevent tight packing.

Question 6

Which of the following best describes the function of transmembrane proteins in the plasma membrane?

Accepted Answer

They span the lipid bilayer and can facilitate transport, signal transduction, or cell-cell communication.

Question 7

A mutation causes a cell to produce a membrane with phospholipids containing fatty acid chains shorter than 16 carbons. What is the most likely consequence?

Accepted Answer

Membrane fluidity will increase.

Question 8

Which of the following is a real-world example of membrane asymmetry affecting cell function?

Accepted Answer

Presence of carbohydrate groups on the outer surface of red blood cells determining ABO blood type.

Question 9

Which equation best describes the movement of ions across a membrane due to a concentration gradient?

Accepted Answer

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

Question 10

A cell is placed in a solution containing a high concentration of Na	extsuperscript{+}. Which membrane protein is most likely to be involved in maintaining the cell's internal environment?

Accepted Answer

Na	extsuperscript{+}/K	extsuperscript{+} ATPase pump

Question 11

Which of the following membrane proteins is covalently linked to glycosylphosphatidylinositol (GPI)?

Accepted Answer

GPI-anchored membrane protein

Question 12

Which process is most directly responsible for the selective permeability of the plasma membrane?

Accepted Answer

Specific transport proteins embedded in the membrane

Question 13

A patient with a genetic defect in gap junction proteins would most likely experience problems in which cellular process?

Accepted Answer

Cell-cell communication

Question 14

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

Accepted Answer

It acts as a spacer between phospholipids, increasing membrane fluidity.

Question 15

Which type of membrane transport protein allows water molecules to move rapidly across the plasma membrane?

Accepted Answer

Aquaporin channel

Question 16

Which of the following is a multi-step process involving both direct and indirect active transport in a cell?

Accepted Answer

Coupled transport where Na	extsuperscript{+} gradient created by ATPase is used to drive glucose uptake via a symporter

Question 17

Which of the following is a function of the glycocalyx on the surface of animal cells?

Accepted Answer

Facilitating cell-cell recognition

Question 18

Which of the following best describes the difference between channel proteins and carrier proteins in membrane transport?

Accepted Answer

Channel proteins form hydrophilic pores for passive transport; carrier proteins bind solutes and change conformation to move them across the membrane.

Question 19

Which of the following membrane proteins is most likely to be involved in autophagy?

Accepted Answer

Enzymes localized to specific membranes

Cell Membranes: Structure, Function, and Chemistry

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