Question 1

Which of the following best explains how enzymes speed up chemical reactions in biological systems?

Accepted Answer

They lower the activation energy barrier required for the reaction to proceed.

Question 2

A scientist is studying the effect of pH on the activity of an enzyme that functions in the human stomach. Which of the following is most likely to occur if the pH is increased from 2 to 7?

Accepted Answer

The enzyme will denature, causing a decrease in its activity.

Question 3

Which of the following statements correctly distinguishes between competitive and noncompetitive (allosteric) enzyme inhibitors?

Accepted Answer

Competitive inhibitors bind to the active site, while noncompetitive inhibitors bind to a different site on the enzyme.

Question 4

During cellular respiration, which molecule acts as the final electron acceptor in the electron transport chain, and what is the resulting product?

Accepted Answer

Oxygen; water

Question 5

A patient is experiencing muscle fatigue during intense exercise due to a lack of oxygen. Which process is primarily responsible for the continued production of ATP in their muscle cells under these conditions?

Accepted Answer

Lactic acid fermentation

Question 6

Which of the following best describes the role of NADH and FADH$$_2 in $$cellular respiration?

Accepted Answer

They are electron carriers that transport high-energy electrons to the electron transport chain.

Question 7

Which of the following equations correctly represents the overall process of cellular respiration?

Accepted Answer

$$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\ \mathrm{O}_2 ightarrow 6\ \mathrm{CO}_2 + 6\ \mathrm{H}_2\mathrm{O} + 	ext{energy}$$

Question 8

Why does the inner membrane of the mitochondria have a larger surface area than the outer membrane, and how does this relate to ATP production?

Accepted Answer

It provides more area for the electron transport chain and ATP synthase, leading to greater ATP production during oxidative phosphorylation.

Question 9

Which of the following best explains why glycolysis can continue in the absence of oxygen?

Accepted Answer

Fermentation recycles NADH back to NAD$$^+$$, allowing glycolysis to continue producing ATP.

Question 10

A plant cell is exposed to a toxin that blocks the function of ATP synthase in the thylakoid membrane. Which process will be directly affected?

Accepted Answer

The Calvin cycle will stop because ATP cannot be produced in the light reactions.

Question 11

Which of the following is a correct comparison between the light reactions of photosynthesis and the electron transport chain of cellular respiration?

Accepted Answer

Both use ATP synthase to produce ATP by utilizing a proton gradient across a membrane.

Question 12

Which of the following best describes the function of stomata in plant leaves during photosynthesis?

Accepted Answer

They allow the exchange of gases, letting CO$$_2 in $$and O$$_2$$ out.

Question 13

Which of the following is the correct sequence of events in aerobic cellular respiration?

Accepted Answer

Glycolysis $$\rightarrow$$ Krebs Cycle $$\rightarrow$$ Electron Transport Chain

Question 14

A mutation causes a plant to lack the pigment chlorophyll b. What is the most likely consequence for the plant?

Accepted Answer

The plant will absorb a narrower range of light wavelengths, reducing photosynthetic efficiency.

Question 15

Which of the following statements about the Calvin Cycle is correct?

Accepted Answer

It takes place in the stroma of the chloroplast and uses ATP and NADPH to build glucose from CO$$_2.$$

Question 16

Which of the following best describes the relationship between photosynthesis and cellular respiration in the global carbon cycle?

Accepted Answer

Photosynthesis removes CO$$_2$$ from the atmosphere and produces O$$_2$$, while cellular respiration uses O$$_2$$ and releases CO$$_2.$$

Question 17

A cell is placed in an environment with a high concentration of substrate for a particular enzyme. What will happen to the rate of the enzyme-catalyzed reaction as substrate concentration increases, assuming enzyme concentration remains constant?

Accepted Answer

The reaction rate will increase and then level off when the enzyme becomes saturated.

Question 18

Which of the following is a product of the splitting of water during the light reactions of photosynthesis, and what is its fate?

Accepted Answer

O$$_2$$; released as a waste gas into the atmosphere

Question 19

Which of the following best explains why the Krebs cycle runs twice for each molecule of glucose that enters cellular respiration?

Accepted Answer

Each glucose molecule produces two pyruvate molecules, each of which enters the Krebs cycle.

Unit 3 Test Review Guide: Metabolism, Cellular Respiration, and Photosynthesis

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