Q: The sodium-potassium pump moves ions across the plasma membrane. Which equation best represents its action per ATP hydrolyzed?

$$\text{3 } \mathrm{Na^+}$$ out, $$\text{2 } \mathrm{K^+} in$

Question 1

Which of the following best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

A flexible structure where phospholipids, proteins, cholesterol, and carbohydrates move within or along the membrane.

Question 2

A red blood cell is placed in a hypertonic solution. What is the expected outcome, and why?

Accepted Answer

The cell will shrink because water moves out toward the higher solute concentration outside.

Question 3

Which of the following molecules is most likely to cross the phospholipid bilayer by simple diffusion?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 4

Which statement correctly distinguishes between simple diffusion and facilitated diffusion?

Accepted Answer

Facilitated diffusion requires a transport protein, while simple diffusion does not.

Question 5

The sodium-potassium pump moves ions across the plasma membrane. Which equation best represents its action per ATP hydrolyzed?

Accepted Answer

$$	ext{3 } \mathrm{Na^+}$$ out, $$	ext{2 } \mathrm{K^+} in$

Question 6

Which of the following is an example of coupled transport in cells?

Accepted Answer

Sodium ions moving into the cell down their gradient, providing energy to transport another molecule against its gradient.

Question 7

Which process is responsible for the selective uptake of specific molecules, such as cholesterol, into a cell?

Accepted Answer

Receptor-mediated endocytosis

Question 8

A plant cell is placed in a hypotonic solution. What happens to the cell, and why?

Accepted Answer

The cell becomes turgid as water enters, but the cell wall prevents bursting.

Question 9

Which of the following statements about ATP hydrolysis is correct?

Accepted Answer

ATP hydrolysis releases free energy that can be used for cellular work.

Question 10

Which equation correctly represents ATP hydrolysis?

Accepted Answer

$$\mathrm{ATP + H_2O \rightarrow ADP + P_i}$$

Question 11

Which of the following best describes an exergonic reaction?

Accepted Answer

A reaction with $$\Delta G \u003c 0$$ that releases free energy and is thermodynamically spontaneous.

Question 12

Which statement about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy and speed up reactions without being consumed.

Question 13

A metabolic pathway is illustrated as $$\mathrm{A \rightarrow B \rightarrow C \rightarrow D}. If $$the final product D inhibits the enzyme that converts A to B, what is this regulatory mechanism called?

Accepted Answer

Feedback inhibition

Question 14

Which of the following is true regarding the Second Law of Thermodynamics?

Accepted Answer

Every energy transfer or transformation increases the total entropy of the universe.

Question 15

Which of the following is an example of an anabolic pathway?

Accepted Answer

The synthesis of proteins from amino acids.

Question 16

Which factor would most likely decrease membrane fluidity?

Accepted Answer

Decreasing temperature.

Question 17

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzyme specificity is determined by the structure and chemical properties of the active site.

Question 18

Which of the following is a correct example of a redox reaction in biology?

Accepted Answer

Glucose is oxidized during cellular respiration, losing electrons.

Question 19

Which statement about allosteric regulation is correct?

Accepted Answer

Allosteric regulation involves binding at a site other than the active site, changing protein activity.

Plasma Membranes, Energy, and Metabolism: Study Guide for General Biology

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