Question 1

A researcher is studying the movement of a small, uncharged, hydrophobic molecule across a cell membrane. Which of the following best describes how this molecule will cross the membrane?

Accepted Answer

It will diffuse directly through the lipid bilayer down its concentration gradient without the need for energy.

Question 2

Which of the following statements correctly distinguishes between a channel and a pump in membrane transport?

Accepted Answer

Channels allow substances to move down their concentration gradient without energy input, while pumps use ATP to move substances against their gradient.

Question 3

A cell is placed in a solution where the concentration of water is higher outside the cell than inside. What will happen to the cell, and what process is responsible?

Accepted Answer

Water will move into the cell by osmosis, causing the cell to swell.

Question 4

Which of the following best explains why the Na+/K+ ATPase pump is essential for secondary active transport in animal cells?

Accepted Answer

It establishes a sodium gradient by pumping Na+ out of the cell, which can then be used by co-transporters to move other substances against their gradients.

Question 5

A scientist measures the free energy change ($$\Delta G) of a $$reaction and finds $$\Delta G = +5 kJ/$$mol. Which of the following is true about this reaction?

Accepted Answer

The reaction is endergonic and will not occur spontaneously.

Question 6

Which of the following best describes how the hydrolysis of ATP is used to drive endergonic reactions in cells?

Accepted Answer

ATP hydrolysis is coupled to endergonic reactions by transferring a phosphate group to a reactant, making the overall $$\Delta G$$ negative.

Question 7

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy of a reaction but do not change the $$\Delta G.$$

Question 8

A mutation changes the shape of the active site of an enzyme. What is the most likely consequence of this mutation?

Accepted Answer

The enzyme may no longer bind its substrate effectively, reducing the rate of catalysis.

Question 9

Which of the following best explains why a human enzyme that evolved to function at body temperature (37°C) might not work well at 60°C?

Accepted Answer

The enzyme's structure may denature at higher temperatures, reducing its catalytic activity.

Question 10

During aerobic cellular respiration, which stage directly requires molecular oxygen ($$O_2$$)?

Accepted Answer

Electron transport chain

Question 11

If the electron transport chain in mitochondria is inhibited, what will be the immediate effect on the citric acid cycle?

Accepted Answer

The citric acid cycle will slow down or stop because NAD+ and FAD will not be regenerated.

Question 12

A patient is found to have high levels of pyruvate in their cells. Which of the following is the most likely explanation?

Accepted Answer

There is a problem with the transition reaction (pyruvate oxidation), preventing pyruvate from being converted to acetyl-CoA.

Question 13

Which of the following statements about the fate of oxygen atoms during cellular respiration is correct?

Accepted Answer

The oxygen atoms in $$CO_2$$ come from the glucose molecule.

Question 14

Which of the following best describes the main way in which organisms lose mass during weight loss?

Accepted Answer

By releasing carbon as $$CO_2$$ during cellular respiration.

Question 15

A cell is placed in a solution containing a high concentration of glucose, but the cell membrane is impermeable to glucose and there are no glucose transporters present. What will happen to the glucose?

Accepted Answer

Glucose will not enter the cell because there is no specific channel, transporter, or pump for it.

Question 16

Which of the following scenarios best illustrates the concept of coupling an exergonic and an endergonic reaction in a living cell?

Accepted Answer

The breakdown of glucose to $$CO_2$$ and $$H_2O$$ releases energy, which is used to synthesize ATP from ADP and $$P_i.$$

Question 17

Which of the following is a correct statement about osmosis?

Accepted Answer

Osmosis is the diffusion of water across a selectively permeable membrane.

Question 18

A cell uses a co-transporter to move glucose into the cell against its concentration gradient. Which of the following best describes how this process works?

Accepted Answer

The co-transporter uses the energy from another substance (such as Na+) moving down its concentration gradient to move glucose against its gradient.

Membrane Transport, Enzyme Function, and Cellular Respiration: Study Guide

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