Question 1

Which of the following best describes how ATP hydrolysis drives the synthesis of glutamine from glutamic acid and ammonia in cells?

Accepted Answer

ATP hydrolysis phosphorylates glutamic acid, creating a high-energy intermediate that reacts with ammonia to form glutamine.

Question 2

Which of the following is NOT a general strategy used by enzymes to catalyze reactions?

Accepted Answer

Enzymes always increase the temperature of the reaction environment.

Question 3

What is the main role of the active site in an enzyme such as lysozyme?

Accepted Answer

To bind the substrate and lower the activation energy by stabilizing the transition state.

Question 4

Which statement best explains allosteric regulation of enzyme activity?

Accepted Answer

Allosteric regulators bind to a site other than the active site, stabilizing either the active or inactive form of the enzyme.

Question 5

Feedback inhibition in metabolic pathways is best described as:

Accepted Answer

The end product of a pathway allosterically inhibits an enzyme that acts early in the pathway.

Question 6

Which of the following equations correctly represents the overall process of photosynthesis in plants?

Accepted Answer

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 7

In the light reactions of photosynthesis, what is the primary function of the electron transport chain between photosystem II and photosystem I?

Accepted Answer

To pump protons into the thylakoid space, creating a gradient used to produce ATP.

Question 8

Which of the following best explains why C4 and CAM plants are adapted to hot, dry environments?

Accepted Answer

They can fix CO2 at night or in specialized cells, reducing water loss while maintaining high CO2/O2 ratios for the Calvin cycle.

Question 9

Which of the following is a correct description of active transport across a membrane?

Accepted Answer

Molecules move against their concentration gradient, requiring energy input, often from ATP hydrolysis.

Question 10

The Na+/K+ ATPase pump is crucial for nerve cell function because it:

Accepted Answer

Uses ATP to move 3 Na+ out of the cell and 2 K+ into the cell, establishing ion gradients necessary for action potentials.

Question 11

Which of the following best describes the role of Rubisco in the Calvin cycle?

Accepted Answer

It catalyzes the fixation of CO2 to ribulose bisphosphate, initiating the Calvin cycle.

Question 12

Which of the following is a key difference between competitive and non-competitive enzyme inhibition?

Accepted Answer

Competitive inhibitors bind to the active site, while non-competitive inhibitors bind to a different site on the enzyme.

Question 13

Which of the following statements about membrane transport proteins is TRUE?

Accepted Answer

Channel proteins allow specific ions or molecules to pass through membranes rapidly, often in response to stimuli.

Question 14

Which process is responsible for the rapid transmission of nerve impulses along an axon?

Accepted Answer

Opening and closing of voltage-gated Na+ and K+ channels, generating action potentials.

Question 15

Which of the following best explains why metabolic pathways in cells do not reach equilibrium?

Accepted Answer

The product of one reaction is quickly used as the substrate for the next reaction, maintaining metabolic disequilibrium.

Question 16

Which of the following is a real-world example of feedback inhibition in metabolism?

Accepted Answer

The end product isoleucine inhibits threonine deaminase, the first enzyme in its biosynthetic pathway.

Question 17

Which of the following best describes the effect of temperature on enzyme activity?

Accepted Answer

Enzyme activity increases with temperature up to an optimum, then decreases as the enzyme denatures.

Question 18

Which of the following is a correct statement about the role of uncoupler proteins in mitochondria?

Accepted Answer

They dissipate the proton gradient, releasing energy as heat instead of producing ATP.

Question 19

Which of the following best explains why plants appear green?

Accepted Answer

Chlorophyll reflects and transmits green light, while absorbing red and blue wavelengths.

Cellular Metabolism, Enzyme Function, and Membrane Transport: Core Concepts in Cellular Biology

Study Guide - Practice Questions