Question 1

Which of the following best describes the primary function of the plasma (cellular) membrane in eukaryotic cells?

Accepted Answer

It regulates the passage of materials into and out of the cell, maintaining homeostasis.

Question 2

Which plasma membrane component is primarily responsible for forming the basic structural framework of the membrane?

Accepted Answer

Phospholipid bilayer

Question 3

A cell is placed in a hypotonic solution. What will most likely happen to the cell due to osmoregulation?

Accepted Answer

The cell will gain water and swell, possibly bursting.

Question 4

Which of the following is NOT a function of plasma membrane proteins?

Accepted Answer

Storing genetic information for the cell

Question 5

Facilitated diffusion is a type of passive transport. Which statement best describes how it differs from simple diffusion?

Accepted Answer

Facilitated diffusion uses membrane proteins to move substances down their concentration gradient.

Question 6

Which equation correctly represents the change in free energy ($\Delta G$) for a chemical reaction?

Accepted Answer

$\Delta G = \Delta H - T\Delta S$

Question 7

Which of the following statements about exergonic and endergonic reactions is correct?

Accepted Answer

Exergonic reactions release energy and have a negative $\Delta G$.

Question 8

A ligand-gated ion channel is important in cell signaling because:

Accepted Answer

It allows ions to pass through the membrane only when a specific ligand binds, enabling rapid cellular responses.

Question 9

Which of the following best explains how enzymes speed up chemical reactions?

Accepted Answer

Enzymes lower the activation energy ($E_a$) required for the reaction.

Question 10

Which factor would NOT directly affect enzyme activity in a cell?

Accepted Answer

The concentration of DNA in the nucleus

Question 11

Which of the following is an example of active transport across a plasma membrane?

Accepted Answer

Sodium-potassium pump moving Na$^+$ out and K$^+$ into the cell against their concentration gradients

Question 12

Which type of plasma membrane protein is most likely to be involved in cell-to-cell recognition?

Accepted Answer

Glycoproteins

Question 13

Which process is responsible for the movement of water across a cell membrane?

Accepted Answer

Osmosis

Question 14

Which of the following best describes metabolism?

Accepted Answer

All chemical reactions that occur within a living organism, including both catabolism and anabolism

Question 15

How do catabolism and anabolism differ?

Accepted Answer

Catabolism breaks down molecules to release energy, while anabolism uses energy to build complex molecules.

Question 16

A patient is experiencing muscle cramps due to low potassium levels. Which plasma membrane process is most likely impaired?

Accepted Answer

Active transport via the sodium-potassium pump

Question 17

Which of the following statements about membrane carbohydrates is correct?

Accepted Answer

They play a key role in cell recognition and signaling.

Question 18

Which of the following would most likely increase the rate of an enzyme-catalyzed reaction?

Accepted Answer

Adding more substrate up to the enzyme's saturation point

Question 19

A cell needs to import a large molecule that cannot pass through the membrane by diffusion or transport proteins. Which process will it most likely use?

Accepted Answer

Endocytosis

Question 20

Which of the following is true regarding the role of cholesterol in the plasma membrane?

Accepted Answer

Cholesterol stabilizes membrane fluidity across temperature changes.

Cell Membranes, Transport, and Enzyme Function: General Biology Study Notes

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