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 energy to move substances against their concentration gradient.

Question 3

A cell is placed in a solution where the concentration of solutes outside the cell is higher than inside. 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 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 ATP hydrolysis can drive an endergonic reaction in a cell?

Accepted Answer

ATP hydrolysis releases energy that is transferred to the endergonic reaction by direct contact or phosphorylation, 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 for the enzyme's function?

Accepted Answer

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

Question 9

Which of the following best explains why enzymes that evolved in a specific environment (e.g., high temperature) may not function well in a different environment?

Accepted Answer

Enzyme activity depends on the shape and charge of the active site, which can be altered by changes in temperature or pH.

Question 10

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

Accepted Answer

Electron transport chain (oxidative phosphorylation)

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 due to a lack of NAD+ and FAD.

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

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

Question 13

Which of the following statements about osmosis is correct?

Accepted Answer

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

Question 14

A cell is placed in a solution containing a high concentration of glucose, but the cell membrane is impermeable to glucose. What will happen to the movement of glucose and water?

Accepted Answer

Glucose will not move, but water will move out of the cell by osmosis.

Question 15

Which of the following best describes the fate of the oxygen atoms from $$O_2$$ that are inhaled during aerobic respiration?

Accepted Answer

They are incorporated into water ($$H_2O) $$produced at the end of the electron transport chain.

Question 16

Which of the following is true regarding the conservation of matter and energy in biological systems?

Accepted Answer

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

Question 17

A person loses weight primarily through which of the following processes at the molecular level?

Accepted Answer

Loss of carbon atoms as $$CO_2$$ during cellular respiration.

Question 18

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

Accepted Answer

The hydrolysis of ATP ($$ATP \rightarrow ADP + P_i) is $$used to drive the synthesis of glucose from smaller molecules.

Question 19

Which of the following is a correct statement about the movement of different solutes across a membrane?

Accepted Answer

Each solute moves independently down its own concentration gradient, unless a co-transporter is involved.

Membrane Transport, Energy, Enzymes, and Cellular Respiration: Study Guide

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