1 If excess ADP were artificially introduced into the cytopl

1) If excess ADP were artificially introduced into the cytoplasm of a cell, what would the likely effect be?

Question 5 options:

A:stimulate glycolysis by activating phosphofructokinase

B:stimulate the Krebs cycle by activating pyruvate dehydrogenase

C:stimulate the oxidation of pyruvate by activating pyruvate dehydrogenase

D:inhibit glycolysis by inactivating phosphofructokinase

E:inhibit glycolysis by inactivating citrate synthetase

2) Glycolysis produces ATP by:

Question 7 options:

A:electrochemical gradient.

B:substrate-level phosphorylation.

C:oxidative phosphorylation.

D:ATP synthase.

3) How many ATP are produced directly through the oxidation of a single pyruvate?

Question 10 options:

A:0

B:1

C:2

D:4

4)The Krebs cycle starts and ends with the four-carbon molecule:

Question 13 options:

A:citrate.

B:pyruvate.

C:ethanol.

D:lactate.

E:oxaloacetate.

6)Which of the following molecules is produced with the expenditure of NADH during fermentation?

Question 21 options:

A:citrate

B:CO2

C:pyruvate

D:oxygen

E:lactate

Solution

Answer : Question number 1 : The correct answer is A (stimulate glycolysis by activating phosphofructokinase).

Explanation : Phosphofructokinase 1 catalyses the transfer of phosphoryl group from ATP to fructose 6- phosphate to yield fructose 1, 6- bisphosphate and also the major regulatory enzyme of glycolysis. The activity of PFK-1 is increased whenever the cells ATP supply is depleted or when the ATP break dwon products ADP and AMP, particularly AMP are in excess.

Question number 2 : The correct answer is B ( substrate-level phosphorylation). The 7^th reaction catalysed by Phosphoglycerate kinase and the 10^th reaction catalysed by Pyruvate kinase are involved in the substrate level phosphorylation