Question 1

A researcher adds a hydrophilic molecule to the extracellular fluid surrounding a cell. Which of the following best predicts how this molecule will enter the cell?

Accepted Answer

It will require a specific channel or transporter protein to cross the membrane.

Question 2

Which of the following statements correctly distinguishes between channels and pumps in cellular membranes?

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 is the process called?

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 hydrolysis of ATP is often coupled to endergonic reactions in cells?

Accepted Answer

ATP hydrolysis provides energy, making the overall $$\Delta G of $$the coupled reactions negative.

Question 5

A mutation changes the shape of an enzyme's active site. Which of the following is the most likely consequence?

Accepted Answer

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

Question 6

Which of the following statements about cellular respiration is correct?

Accepted Answer

Only the electron transport chain directly requires $$O_2$$; other stages depend on it indirectly.

Question 7

A scientist blocks the electron transport chain in a cell. What is the most immediate effect on cellular respiration?

Accepted Answer

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

Question 8

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 9

Which of the following is a key difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have a nucleus containing their DNA, while prokaryotic cells do not.

Question 10

A cell is exposed to a hydrophobic signaling molecule. Where is its receptor most likely located?

Accepted Answer

Inside the cell, in the cytoplasm or nucleus.

Question 11

Which of the following best explains why enzymes do not make non-spontaneous reactions spontaneous?

Accepted Answer

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

Question 12

Which of the following is true regarding osmosis?

Accepted Answer

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

Question 13

A patient is given a drug that inhibits phosphorylation during cell signaling. Which stage of cell signaling is most directly affected?

Accepted Answer

Signal transduction

Question 14

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

Accepted Answer

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

Question 15

Which of the following is a correct statement about the endomembrane system in eukaryotic cells?

Accepted Answer

It consists of the endoplasmic reticulum, Golgi apparatus, lysosomes, and vesicles.

Question 16

Which of the following scenarios would most likely result in an increase in the rate of an enzyme-catalyzed reaction?

Accepted Answer

Adding more substrate when the enzyme is not saturated.

Question 17

Which of the following best explains why the mass of an organism decreases during cellular respiration?

Accepted Answer

Carbon atoms are released as $$CO_2$$ during respiration and exhaled.

Question 18

Which of the following is true about the movement of substances across a biological membrane?

Accepted Answer

Each substance moves according to its own concentration gradient, independent of others.

Question 19

Which of the following best describes the difference between exergonic and endergonic reactions?

Accepted Answer

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

UCSD BILD 1: The Cell - Exam 2 Study Guide

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