Question 1

Which of the following best explains why phospholipids spontaneously form a bilayer in aqueous environments?

Accepted Answer

Their hydrophilic heads interact with water, while their hydrophobic tails avoid water, resulting in a bilayer.

Question 2

A scientist observes a membrane protein that spans the entire phospholipid bilayer and has both hydrophobic and hydrophilic regions. Which type of protein is this, and why must it have these properties?

Accepted Answer

Integral protein; it must be amphipathic to interact with both the hydrophobic core and aqueous environments.

Question 3

Which of the following molecules would cross a pure phospholipid bilayer most rapidly, and why?

Accepted Answer

O$$_2$$, because it is small and nonpolar.

Question 4

Cholesterol is an important component of animal cell membranes. What is its primary function at low temperatures?

Accepted Answer

It prevents phospholipids from packing too tightly, maintaining fluidity.

Question 5

A mutation causes aquaporin proteins in kidney cells to become nonfunctional. What is the most likely physiological consequence?

Accepted Answer

Water will cross the membrane at a much slower rate, leading to dehydration.

Question 6

Which statement best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

A fluid bilayer of phospholipids with embedded amphipathic proteins that can move laterally.

Question 7

During cellular respiration, which process directly produces ATP via substrate-level phosphorylation?

Accepted Answer

Glycolysis and the citric acid cycle

Question 8

Which sequence correctly represents the stages of cellular respiration from start to finish?

Accepted Answer

Glucose → Glycolysis → Pyruvate Oxidation → Citric Acid Cycle → Oxidative Phosphorylation

Question 9

In the electron transport chain, what is the primary role of NADH and FADH$$_2$$?

Accepted Answer

They donate electrons to the chain, providing energy to pump H$$^{+}$$ across the inner mitochondrial membrane.

Question 10

A patient is exposed to a toxin that blocks the movement of H$$^{+}$$ ions across the inner mitochondrial membrane. Which process will be most directly affected?

Accepted Answer

ATP synthesis by oxidative phosphorylation

Question 11

Which of the following is a correct description of oxidation and reduction in cellular respiration?

Accepted Answer

Oxidation is the loss of electrons; reduction is the gain of electrons.

Question 12

Which of the following is NOT a product of glycolysis from one molecule of glucose?

Accepted Answer

2 molecules of FADH$$_2$$

Question 13

A carrier protein in the plasma membrane is found to transport only glucose, not fructose, even though both are structural isomers. What property of carrier proteins does this illustrate?

Accepted Answer

Carrier proteins are specific to the molecules they transport.

Question 14

Which of the following best describes the arrangement of the mitochondrial inner membrane and its significance?

Accepted Answer

It is folded into cristae to increase surface area for ATP-producing enzymes.

Question 15

Which of the following statements about membrane proteins is correct?

Accepted Answer

Integral proteins are amphipathic and interact with both hydrophobic and hydrophilic regions.

Question 16

If a cell is placed in a solution containing a high concentration of a small, nonpolar molecule such as O$$_2$$, what will most likely happen?

Accepted Answer

O$$_2$$ will diffuse rapidly across the membrane without the need for a transport protein.

Question 17

Which of the following is a direct result of the lateral movement of phospholipids within the membrane?

Accepted Answer

The membrane remains fluid and flexible under normal conditions.

Question 18

During the citric acid cycle, which of the following is produced per turn of the cycle (per acetyl-CoA)?

Accepted Answer

2 NADH, 1 FADH$$_2$$, 1 ATP (or GTP)

Question 19

Which of the following best explains why O$$_2 is $$required for cellular respiration?

Accepted Answer

O$$_2$$ acts as the final electron acceptor in the electron transport chain, allowing ATP production.

Cell Membrane Structure, Membrane Transport, and Cellular Respiration Study Guide

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