Question 1

Which of the following best describes the process of extracellular digestion in microbes?

Accepted Answer

Microbes release exoenzymes to break down complex carbohydrates outside the cell before uptake.

Question 2

During glycolysis, what is the net gain of ATP and NADH molecules per molecule of glucose?

Accepted Answer

$$2$$ ATP and $$2$$ NADH

Question 3

Which enzyme catalyzes the phosphorylation of glucose in the first step of glycolysis?

Accepted Answer

Hexokinase

Question 4

What is the fate of pyruvate in a eukaryotic cell under aerobic conditions?

Accepted Answer

It is converted to acetyl-CoA in the mitochondria and enters the citric acid cycle.

Question 5

Which step in glycolysis is considered the main regulatory and rate-limiting step?

Accepted Answer

Step 3: Phosphorylation of fructose-6-phosphate by phosphofructokinase-1

Question 6

In the citric acid cycle, which molecule combines with acetyl-CoA to form citrate?

Accepted Answer

Oxaloacetate

Question 7

Which of the following is a product of the oxidation of pyruvate before entering the citric acid cycle?

Accepted Answer

Acetyl-CoA

Question 8

How many NADH molecules are produced per turn of the citric acid cycle for each acetyl-CoA?

Accepted Answer

$$3$$

Question 9

Which short-chain fatty acid produced by gut microbes is most associated with anti-inflammatory effects and regulatory T cell production?

Accepted Answer

Butyrate

Question 10

A patient has a mutation that impairs the function of phosphofructokinase-1 (PFK-1). Which step of glycolysis is directly affected?

Accepted Answer

Conversion of fructose-6-phosphate to fructose 1,6-bisphosphate

Question 11

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

Accepted Answer

Glycolysis does not require oxygen and occurs in the cytoplasm.

Question 12

Which enzyme catalyzes the conversion of malate to oxaloacetate in the citric acid cycle?

Accepted Answer

Malate dehydrogenase

Question 13

What is the main function of short-chain fatty acids (SCFAs) produced by gut microbes?

Accepted Answer

They act as anti-inflammatory signals and strengthen the gut barrier.

Question 14

Which of the following is NOT a product of one turn of the citric acid cycle per acetyl-CoA?

Accepted Answer

$$2$$ $$FADH_2$

Question 15

A researcher is studying the effects of a drug that inhibits the enzyme aldolase. Which glycolytic step will be blocked?

Accepted Answer

Cleavage of fructose 1,6-bisphosphate into two triose phosphates

Question 16

Which of the following statements about the fate of pyruvate is correct?

Accepted Answer

Pyruvate can be converted to acetyl-CoA in the presence of oxygen.

Question 17

Which metabolic product of microbial tryptophan catabolism interacts with the Aryl Hydrocarbon Receptor (Ahr) to modulate immune responses?

Accepted Answer

Indoles

Question 18

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

Direct transfer of a phosphate group to ADP from a high-energy substrate

Question 19

A patient with a deficiency in butyrate-producing gut bacteria is most likely to experience which of the following?

Accepted Answer

Weakened gut barrier and increased inflammation

lec 17:Microbial Metabolism: Glycolysis, Citric Acid Cycle, and Microbial Metabolites

Study Guide - Practice Questions