Question 1

Which of the following statements best explains why ATP hydrolysis is considered an exergonic reaction?

Accepted Answer

It releases free energy that can be used to drive endergonic cellular processes.

Question 2

A scientist measures the change in free energy ($$\Delta G) $$for a chemical reaction and finds $$\Delta G = -15 kJ/$$mol. Which of the following is true about this reaction?

Accepted Answer

The reaction is exergonic and can occur spontaneously.

Question 3

Which of the following best describes the role of enzymes in biological systems?

Accepted Answer

They lower the activation energy ($$E_a) of $$reactions, increasing the rate without altering $$\Delta G.$$

Question 4

A patient is diagnosed with a genetic disorder that causes a nonfunctional phosphofructokinase (PFK) enzyme. Which metabolic process will be directly affected, and what is the likely consequence?

Accepted Answer

Glycolysis will be inhibited, leading to decreased ATP production from glucose.

Question 5

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

Accepted Answer

Oxygen ($$O_2$$); water ($$H_2O)$$

Question 6

Which of the following best explains why fermentation is necessary in the absence of oxygen?

Accepted Answer

Fermentation regenerates NAD$$^+$$, allowing glycolysis to continue producing ATP.

Question 7

A muscle cell is deprived of oxygen during intense exercise. Which metabolic pathway will the cell rely on for ATP production, and what is the main byproduct?

Accepted Answer

Glycolysis followed by lactic acid fermentation; lactate is produced.

Question 8

Which of the following statements correctly compares substrate-level phosphorylation and oxidative phosphorylation?

Accepted Answer

Substrate-level phosphorylation transfers a phosphate group directly from a substrate to ADP, while oxidative phosphorylation uses a proton gradient to drive ATP synthesis.

Question 9

In the light reactions of photosynthesis, what is the primary function of water ($$H_2O$$)?

Accepted Answer

To provide electrons to Photosystem II, resulting in the release of oxygen gas ($$O_2)$$

Question 10

A plant is exposed only to green light. What is the most likely effect on the rate of photosynthesis, and why?

Accepted Answer

Photosynthesis will decrease because chlorophyll reflects green light rather than absorbing it.

Question 11

Which of the following best describes the flow of electrons during linear electron flow in the light reactions of photosynthesis?

Accepted Answer

$$H_2O \rightarrow$$ Photosystem II $$\rightarrow$$ Electron Transport Chain $$\rightarrow$$ Photosystem I $$\rightarrow$$ NADP^+ \rightarrow$ NADPH

Question 12

Which of the following is a correct statement about the Calvin cycle?

Accepted Answer

It uses ATP and NADPH to convert CO$$_2$$ into G3P, a three-carbon sugar.

Question 13

A cell is exposed to a noncompetitive inhibitor that binds to an enzyme. Which of the following outcomes is most likely?

Accepted Answer

The enzyme's active site changes shape, reducing its ability to bind substrate even if substrate concentration increases.

Question 14

Which of the following best illustrates feedback inhibition in a metabolic pathway?

Accepted Answer

The final product of a pathway binds to an early enzyme, decreasing its activity and slowing further production.

Question 15

Which of the following is a key difference between NADH and NADPH?

Accepted Answer

NADH is primarily involved in cellular respiration, while NADPH is used in photosynthesis.

Question 16

A cell is placed in an environment with a temperature significantly above its optimal range. What is the most likely effect on its enzymes?

Accepted Answer

The enzymes will denature, losing their three-dimensional structure and activity.

Question 17

Which of the following best explains why the citric acid cycle is considered a cycle?

Accepted Answer

Its starting molecule, oxaloacetate, is regenerated at the end of each turn.

Question 18

Which of the following is a correct comparison between chemiosmosis in mitochondria and chloroplasts?

Accepted Answer

Both use a proton gradient and ATP synthase to produce ATP, but the source of energy for the gradient differs.

Question 19

A person is fasting and their body begins to break down stored fats for energy. Which process is responsible for converting fatty acids into molecules that can enter the citric acid cycle?

Accepted Answer

Beta oxidation, which produces acetyl-CoA from fatty acids.

Metabolism, Cellular Respiration, and Photosynthesis: Study Guide

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