Q: Which of the following best explains why coupling the hydrolysis of ATP to an endergonic reaction can make the overall process spontaneous?

The negative $$9;\Delta G\u00039;$$ from ATP hydrolysis can offset the positive $$9;\Delta G\u00039; of $$the endergonic reaction, making the sum negative.

Question 1

A small, nonpolar molecule is present at a higher concentration outside a cell than inside. Which of the following best predicts how this molecule will cross the plasma membrane?

Accepted Answer

It will diffuse directly through the lipid bilayer down its concentration gradient.

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 energy to move substances against their gradient.

Question 3

A cell is placed in a solution with a higher concentration of solutes than inside the cell. What will happen to the water movement, and what is this process called?

Accepted Answer

Water will move out of the cell by osmosis.

Question 4

Which of the following best describes the role of the Na+/K+ ATPase pump in cellular transport?

Accepted Answer

It uses the energy from ATP hydrolysis to move Na+ and K+ ions against their concentration gradients.

Question 5

A scientist measures the $$9;\Delta G\u00039; of a $$reaction and finds it to be negative. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and spontaneous.

Question 6

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy but do not change the $$9;\Delta G\u00039; of a $$reaction.

Question 7

A mutation changes the shape of an enzyme's active site. What is the most likely consequence for the enzyme's function?

Accepted Answer

The enzyme may no longer bind its substrate, reducing or eliminating its catalytic activity.

Question 8

Which of the following best explains why coupling the hydrolysis of ATP to an endergonic reaction can make the overall process spontaneous?

Accepted Answer

The negative $$9;\Delta G\u00039;$$ from ATP hydrolysis can offset the positive $$9;\Delta G\u00039; of $$the endergonic reaction, making the sum negative.

Question 9

Which of the following is true regarding the oxygen atoms in the carbon dioxide ($$\mathrm{CO_2$}) $$produced during cellular respiration?

Accepted Answer

They come from the glucose molecule being broken down.

Question 10

A patient is exposed to a toxin that blocks the electron transport chain in mitochondria. Which of the following will most likely occur as a result?

Accepted Answer

Glycolysis will continue, but the citric acid cycle and oxidative phosphorylation will stop.

Question 11

Which of the following best describes osmosis?

Accepted Answer

The diffusion of water across a selectively permeable membrane.

Question 12

If a cell lacks a specific channel, transporter, or pump for a molecule, how might that molecule still enter the cell?

Accepted Answer

If the molecule is small and hydrophobic, it may diffuse directly through the lipid bilayer.

Question 13

Which of the following statements about the stages of aerobic cellular respiration is correct?

Accepted Answer

Only the electron transport chain directly requires oxygen.

Question 14

A researcher finds that the concentration of pyruvate is abnormally high in a cell. Which of the following is the most likely explanation?

Accepted Answer

The transition reaction is not functioning properly, causing pyruvate to accumulate.

Question 15

Which of the following best explains why organisms lose mass during cellular respiration?

Accepted Answer

Carbon atoms are released as $$\mathrm{CO_2$}$$ during respiration and exhaled.

Question 16

Which of the following is a correct statement about the relationship between exergonic and endergonic reactions?

Accepted Answer

Endergonic reactions have a positive $$\Delta G$$ and require energy input.

Question 17

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

Accepted Answer

The co-transporter couples the movement of glucose with another substance moving down its concentration gradient.

Question 18

Which of the following would most likely decrease the rate of an enzyme-catalyzed reaction in a human cell?

Accepted Answer

Changing the pH far from the enzyme's optimal range.

Question 19

Which of the following best describes the conservation of matter and energy in biological systems?

Accepted Answer

Matter and energy are each conserved; they are transformed but not created or destroyed.

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

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