Question 1

Which component of the plasma membrane is primarily responsible for maintaining membrane fluidity at different temperatures?

Accepted Answer

Cholesterol

Question 2

A red blood cell is placed in a solution and begins to swell until it bursts. What type of solution is the cell in, and what is the direction of water movement?

Accepted Answer

Hypotonic; water moves into the cell

Question 3

Which of the following best describes the function of the sodium-potassium pump?

Accepted Answer

It uses ATP to move 3 Na$$^+$$ ions out of the cell and 2 K$$^+$$ ions into the cell against their concentration gradients.

Question 4

Which process is responsible for the uptake of specific molecules, such as LDL cholesterol, into a cell?

Accepted Answer

Receptor-mediated endocytosis

Question 5

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

Accepted Answer

It will lose water and shrink.

Question 6

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy ($$E_a) of a $$reaction.

Question 7

Which of the following is an example of passive transport?

Accepted Answer

Facilitated diffusion of glucose

Question 8

What is the main difference between simple diffusion and facilitated diffusion?

Accepted Answer

Facilitated diffusion requires transport proteins, while simple diffusion does not.

Question 9

Which law of thermodynamics explains why no energy transformation is 100% efficient and some energy is always lost as heat?

Accepted Answer

Second law of thermodynamics

Question 10

A metabolic pathway is regulated by feedback inhibition. Which of the following best describes this process?

Accepted Answer

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

Question 11

Which of the following best describes the movement of water during osmosis?

Accepted Answer

Water moves from areas of low solute concentration to areas of high solute concentration.

Question 12

Which of the following is true about the energy released from ATP hydrolysis?

Accepted Answer

ATP \rightarrow ADP + P_i$ releases approximately 7.3 kcal/mol of free energy.

Question 13

Which of the following is an example of an allosteric regulation of an enzyme?

Accepted Answer

A molecule binds to a site other than the active site, changing the enzyme's shape and activity.

Question 14

Which of the following best describes the function of glycoproteins in the plasma membrane?

Accepted Answer

They act as cellular ID tags for recognition by the immune system.

Question 15

A cell uses a carrier protein to move glucose into the cell against its concentration gradient, using the energy from the Na$$^+$$ gradient. What type of transport is this?

Accepted Answer

Secondary active transport (coupled transport)

Question 16

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

Accepted Answer

Storing genetic information

Question 17

Which of the following statements about oxidation and reduction is correct?

Accepted Answer

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

Question 18

Which factor would most likely increase the fluidity of a cell membrane?

Accepted Answer

A higher proportion of unsaturated fatty acids in the phospholipids

Question 19

Which of the following best explains why enzymes are specific to their substrates?

Accepted Answer

The active site of an enzyme has a unique shape that fits only specific substrates.

Question 20

A patient is given an intravenous (IV) solution that is isotonic to their blood cells. What will happen to the patient's red blood cells?

Accepted Answer

There will be no net movement of water, and the cells will maintain their normal shape.

Membranes, Transport, Energy & Enzymes: BIO 103 Exam #3 Study Guide

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