Question 1

Which of the following best describes an amphipathic molecule?

Accepted Answer

A molecule that has both hydrophobic and hydrophilic regions.

Question 2

A patient is given an intravenous solution that is hypertonic relative to their red blood cells. What is the most likely outcome for the red blood cells?

Accepted Answer

They will lose water and shrivel.

Question 3

Which of the following statements about the sodium-potassium pump is correct?

Accepted Answer

It moves sodium ions out of the cell and potassium ions into the cell using ATP.

Question 4

Which of the following best explains how cholesterol acts as a 'fluid buffer' in animal cell membranes?

Accepted Answer

Cholesterol reduces membrane fluidity at moderate temperatures but prevents solidification at low temperatures.

Question 5

A plant cell is placed in a hypotonic solution. What is the most likely outcome, and why does this differ from an animal cell in the same solution?

Accepted Answer

The plant cell will become turgid due to water influx, but the cell wall prevents bursting.

Question 6

Which of the following is the main function of carbohydrates in the plasma membrane?

Accepted Answer

Cell-to-cell recognition and distinguishing self from non-self.

Question 7

Arrange the following molecules in order from MOST to LEAST likely to diffuse directly across a lipid bilayer: small nonpolar molecules, large polar molecules, small polar molecules, ions.

Accepted Answer

Small nonpolar molecules \u003e small polar molecules \u003e large polar molecules \u003e ions

Question 8

Which of the following best describes the difference between passive and active transport across a cell membrane?

Accepted Answer

Active transport requires energy to move solutes against their concentration gradient, while passive transport does not require energy and moves solutes down their gradient.

Question 9

A scientist is studying a membrane protein that is embedded within the lipid bilayer and spans the entire membrane. This protein is best classified as:

Accepted Answer

An integral membrane protein

Question 10

Which of the following best describes the process of receptor-mediated endocytosis?

Accepted Answer

The cell takes in specific molecules by using vesicles with proteins that have receptor sites for those molecules.

Question 11

Which of the following is an example of an anabolic pathway, and what is its energy profile?

Accepted Answer

Protein synthesis from amino acids; endergonic

Question 12

According to the first law of thermodynamics, which of the following statements is true?

Accepted Answer

Energy can be transferred and transformed, but it cannot be created or destroyed.

Question 13

A reaction has a $$\Delta G of$$ $$-15 kJ/$$mol. Which of the following statements is correct?

Accepted Answer

The reaction is exergonic and spontaneous.

Question 14

How do enzymes speed up chemical reactions?

Accepted Answer

By lowering the activation energy required for the reaction.

Question 15

Which of the following best describes feedback inhibition in a metabolic pathway?

Accepted Answer

The end product of the pathway inhibits an enzyme that acts early in the pathway.

Question 16

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 17

A lysosomal enzyme has an optimal pH of 4.5. What would you expect to happen to its activity at pH 7?

Accepted Answer

The enzyme's activity would decrease significantly.

Question 18

Which of the following best describes allosteric regulation of an enzyme?

Accepted Answer

A regulatory molecule binds to a site other than the active site, altering enzyme activity.

Question 19

Which of the following best explains why unsaturated fatty acids increase membrane fluidity at lower temperatures?

Accepted Answer

Their hydrocarbon tails prevent tight packing, increasing fluidity.

Question 20

Which of the following is true regarding the second law of thermodynamics?

Accepted Answer

Every energy transfer or transformation increases the entropy of the universe.

BIO 120 Study Guide: Membranes and Enzymes (General Biology)

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