Question 1

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

An enzyme directly transfers a phosphate group from an organic substrate to ADP, forming ATP.

Question 2

During intense exercise, human muscle cells primarily generate ATP through which process when oxygen is limited?

Accepted Answer

Lactic acid fermentation

Question 3

Which of the following equations correctly represents the core reaction of ATP synthesis during phosphorylation?

Accepted Answer

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

Question 4

Which of the following is NOT a product of glycolysis?

Accepted Answer

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

Question 5

A baker is using yeast to make bread. Which metabolic pathway is responsible for the dough rising, and what is the gas produced?

Accepted Answer

Alcoholic fermentation; carbon dioxide ($$\mathrm{CO_2$})$$

Question 6

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation recycles NADH back to NAD$$^+$$, allowing glycolysis to continue producing ATP in the absence of oxygen.

Question 7

Which of the following best explains why glycolysis can occur in both aerobic and anaerobic conditions?

Accepted Answer

Glycolysis does not require oxygen and takes place in the cytoplasm.

Question 8

Which type of phosphorylation is directly powered by light energy absorbed by pigments such as chlorophyll?

Accepted Answer

Photophosphorylation

Question 9

A patient with a rare mitochondrial disorder cannot efficiently perform oxidative phosphorylation. Which of the following would most likely be affected?

Accepted Answer

ATP production during cellular respiration

Question 10

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

Accepted Answer

2 ATP, 2 NADH, 2 pyruvic acid

Question 11

Which of the following commercial products is NOT produced by lactic acid fermentation?

Accepted Answer

Beer

Question 12

In the absence of oxygen, why is fermentation necessary for cells that rely on glycolysis?

Accepted Answer

It regenerates NAD$$^+$$ needed for glycolysis to continue.

Question 13

Which of the following best describes the fate of pyruvic acid in alcoholic fermentation?

Accepted Answer

It is converted into ethanol and carbon dioxide.

Question 14

Which of the following organisms is correctly matched with the type of fermentation it performs?

Accepted Answer

Saccharomyces – alcoholic fermentation

Question 15

A scientist is studying ATP production in a plant cell exposed to light. Which process is primarily responsible for ATP synthesis in the thylakoid membranes?

Accepted Answer

Photophosphorylation

Question 16

Which of the following best explains why fermentation does not produce additional ATP beyond glycolysis?

Accepted Answer

Fermentation only recycles NADH to NAD$$^+$$, allowing glycolysis to continue, but does not generate ATP itself.

Question 17

Which of the following is a key difference between oxidative phosphorylation and substrate-level phosphorylation?

Accepted Answer

Oxidative phosphorylation uses a proton gradient and ATP synthase, while substrate-level phosphorylation involves direct transfer of a phosphate group by an enzyme.

Question 18

Which of the following equations represents the reduction of pyruvic acid during lactic acid fermentation?

Accepted Answer

$$\mathrm{Pyruvic\ Acid} + \mathrm{NADH} \rightarrow \mathrm{Lactic\ Acid} + \mathrm{NAD^+}$$

Question 19

A mutation prevents a bacterium from recycling NADH to NAD$$^+$$ under anaerobic conditions. What is the most likely consequence?

Accepted Answer

Glycolysis will stop due to lack of available NAD$$^+.$$

Question 20

Which of the following best explains why lactic acid fermentation is important in the dairy industry?

Accepted Answer

It produces lactic acid, which is essential for the texture and flavor of products like yogurt and cheese.

Phosphorylation and Fermentation: Mechanisms of Microbial Energy Generation

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