Question 1

Which of the following best describes the main purpose of the preparation (energy investment) phase of glycolysis?

Accepted Answer

To chemically modify glucose by investing ATP, making it more reactive and ready for energy extraction

Question 2

Which enzyme catalyzes the phosphorylation of glucose to glucose-6-phosphate in most tissues?

Accepted Answer

Hexokinase

Question 3

Why is phosphorylation of glucose important during glycolysis?

Accepted Answer

It traps glucose inside the cell and increases its chemical reactivity

Question 4

Which of the following reactions is considered the committed step of glycolysis?

Accepted Answer

Fructose-6-phosphate + ATP \rightarrow Fructose-1,6-bisphosphate + ADP

Question 5

What is the main regulatory enzyme of the preparation phase of glycolysis?

Accepted Answer

Phosphofructokinase-1 (PFK-1)

Question 6

Which molecule acts as an allosteric activator of phosphofructokinase-1 (PFK-1)?

Accepted Answer

AMP

Question 7

A patient has a mutation that reduces glucokinase activity in pancreatic $$ \beta -$$cells. What is the most likely physiological consequence?

Accepted Answer

Impaired glucose sensing and abnormal insulin secretion

Question 8

Which of the following best explains why the reaction catalyzed by hexokinase is essentially irreversible under physiological conditions?

Accepted Answer

It has a large negative change in Gibbs free energy ($$ \Delta G )$$

Question 9

What would be the effect of a specific inhibitor of triose phosphate isomerase on glycolysis?

Accepted Answer

Only one of the two three-carbon products from glucose would proceed through glycolysis, reducing ATP yield

Question 10

Which of the following best describes the role of the induced-fit mechanism in hexokinase function?

Accepted Answer

It positions glucose for efficient phosphate transfer and excludes water from the active site

Question 11

Which of the following is a direct result of the isomerization of glucose-6-phosphate to fructose-6-phosphate?

Accepted Answer

Preparation of the molecule for symmetrical cleavage into two three-carbon sugars

Question 12

In the context of glycolysis, what is meant by a 'committed step'?

Accepted Answer

The first irreversible reaction that commits a metabolite to a specific pathway

Question 13

Which enzyme catalyzes the cleavage of fructose-1,6-bisphosphate into two three-carbon molecules?

Accepted Answer

Aldolase

Question 14

A researcher develops a compound that increases cellular citrate levels. What is the most likely effect on glycolysis?

Accepted Answer

Inhibition of phosphofructokinase-1 and decreased glycolytic flux

Question 15

Which of the following best explains why two ATP molecules are consumed during the preparation phase of glycolysis?

Accepted Answer

To phosphorylate glucose and fructose-6-phosphate, increasing their chemical potential for subsequent reactions

Question 16

Which of the following statements about hexokinase and glucokinase is correct?

Accepted Answer

Glucokinase is found in the liver and pancreatic $$ \beta -$$cells and has a lower affinity for glucose than hexokinase

Question 17

Which of the following best describes the fate of dihydroxyacetone phosphate (DHAP) in glycolysis?

Accepted Answer

It is converted to glyceraldehyde-3-phosphate by triose phosphate isomerase

Question 18

Which of the following best explains the importance of enzyme regulation during the preparation phase of glycolysis?

Accepted Answer

It allows the cell to adjust glycolytic flux according to energy needs and metabolic status

Question 19

A mutation reduces the activity of phosphofructokinase-1 in skeletal muscle. What is the most likely effect during intense exercise?

Accepted Answer

Decreased glycolytic flux and reduced ATP production

Question 20

Which of the following is NOT a product or intermediate of the preparation phase of glycolysis?

Accepted Answer

Pyruvate

The Preparation (Energy Investment) Phase of Glycolysis

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