Question 1

Which of the following best describes the role of phospholipids in the plasma membrane?

Accepted Answer

They form the fundamental structure of the membrane, consisting of hydrophilic heads and hydrophobic tails.

Question 2

A cell is placed in a solution with a higher solute concentration than its cytoplasm. What will most likely happen to the cell?

Accepted Answer

The cell will shrink as water leaves the cell (hypertonic solution).

Question 3

Which process requires energy input in the form of ATP to move solutes against their concentration gradient?

Accepted Answer

Active transport

Question 4

During cellular respiration, which molecule acts as the final electron acceptor in the electron transport chain?

Accepted Answer

Oxygen ($$O_2)$$

Question 5

Which of the following is a correct summary of the net products of glycolysis per glucose molecule?

Accepted Answer

$$2$$ ATP, $$2$$ NADH, $$2$$ pyruvate

Question 6

Which law of thermodynamics explains why some energy is lost as heat during cellular respiration?

Accepted Answer

Second Law: Every energy transfer increases disorder (entropy) and loss of usable energy.

Question 7

Which type of enzyme inhibition involves an inhibitor binding to a site other than the active site, altering the enzyme's shape and function?

Accepted Answer

Noncompetitive inhibition

Question 8

A muscle cell is deprived of oxygen but continues to produce ATP. Which process is most likely responsible for ATP production under these conditions?

Accepted Answer

Fermentation

Question 9

Which of the following best describes the function of receptor proteins in the plasma membrane?

Accepted Answer

They bind signaling molecules and relay messages into the cell.

Question 10

Which stage of cellular respiration produces the most ATP?

Accepted Answer

Oxidative phosphorylation

Question 11

Which of the following equations correctly represents lactic acid fermentation?

Accepted Answer

$$\mathrm{Glucose} \rightarrow \mathrm{Glycolysis} \rightarrow 2 \mathrm{Pyruvate} \rightarrow 2 \mathrm{Lactate}$$

Question 12

Which of the following is NOT a function of proteins embedded in the plasma membrane?

Accepted Answer

Energy production via ATP synthesis

Question 13

A scientist adds a competitive inhibitor to an enzyme-catalyzed reaction. What is the most likely effect?

Accepted Answer

The inhibitor binds to the enzyme's active site, preventing substrate binding.

Question 14

Which of the following best explains why brown fat cells are important for newborn mammals?

Accepted Answer

They use cellular respiration to generate heat without forming ATP.

Question 15

Which step in cellular respiration completes the breakdown of glucose into carbon dioxide and water, producing electron carriers for the next stage?

Accepted Answer

Pyruvate oxidation and the citric acid cycle

Question 16

Which of the following is a real-world example of active transport in human physiology?

Accepted Answer

Sodium-potassium pump maintaining nerve cell membrane potential

Question 17

Which of the following statements about ATP is correct?

Accepted Answer

ATP powers nearly all forms of cellular work, including biochemical, transport, and mechanical work.

Question 18

Which process is responsible for the movement of small nonpolar molecules (e.g., $$O_2$$, $$CO_2) $$across a cell membrane without the use of energy?

Accepted Answer

Simple diffusion

Question 19

During oxidative phosphorylation, what is the main function of the electron transport chain?

Accepted Answer

To transfer electrons and pump protons, creating a gradient used to synthesize ATP

Question 20

Which of the following is a correct equation for alcohol fermentation?

Accepted Answer

$$\mathrm{Glucose} \rightarrow \mathrm{Glycolysis} \rightarrow 2 \mathrm{Pyruvate} \rightarrow 2 \mathrm{Ethanol} + 2 \mathrm{CO}_2$$

The Working Cell: Membranes, Energy, and Cellular Respiration

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