Midterm Mock Test

Question 1

More than one step in the glycolytic pathway is subjected to regulation, why is the first step of glycolysis not the only regulated step?

Answer 1

Some sugars can enter the glycolytic pathway beyond the first step. If steps other than step one was not regulated, the breakdown of these sugars would be essentially uncontrolled.

Question 2

In certain enzyme-catalyzed reaction, the following steps occur:

Step1: A phosphate group on molecule A is transferred to as side chain of an active site residue of the enzyme

Step 2: The dephosphorylated form of molecule A dissociates from the enzyme

Step 3: Molecule B enters the active site and is phosphorylated with simultaneous regeneration of the enzyme in its original form

Step 4: The phosphorylated form of molecule B dissociates from the enzyme

How may you describe the above reaction?

A. Spiral reaction
B. Ordered sequential reaction
C. Random sequential reaction
D. Ping-pong reaction

Answer 2

Ping-pong reaction

Question 3

Which of the following carbohydrate requires the involvement of a nucleotide sugar for its entry to the glycolytic pathway?

A. Fructose
B. Galactose
C. Mannose
D. Sucrose
E. Glycogen

Answer 3

Galactose

Question 4

Which of the following enzymes in glucose metabolism is absent in most tissues except the liver?

A. Hexokinase
B. Glucose 6-phosphatase
C. Phophoglucomutase
D. Glucose 6-phosphate dehydrogenase
E. Pyruvate carboxylase

Answer 4

Glucose 6-phosphatase