BIO 311c
Introductory Biology
K. Sathasivan
In Class Activity 9.2 Respiration
Acetyl CoA Formation and Krebs Cycle
Name ____________________________ Discussion: ____________
A. Multiple Choice Questions
1) More free energy is released during the Krebs cycle than during glycolysis, but only 2 moles
of ATP is produced for each mole of glucose undergoing glycolysis. Most of the remaining
free energy that is produced during the Krebs cycle is used to
A) synthesize GTP.
B) reduce NAD+ and FAD.
C) release as heat.
D) oxidize pyruvate.
E) make ethanol.
2) When mice were fed with radioactive carbon in glucose (C 6H12O6) all the 6 CO2 molecules will
be released during which of the following process
A) Krebs cycle and Oxidative phosphorylation
B) Gycolysis and acetyl CoA formation
C) Glycolysis and Krebs cycle
D) Acetyl CoA formation and Krebs cycle
E) Glycolysis and oxidative phosphorylation
3) When one consumes excess amounts of carbohydrates, they gain weight and store excess
energy as fat. Conversion of carbohydrates to fat will involve the intermediate _________.
A) ATP.
B) Starch.
C) Citrate.
D) NADH.
E) Acetyl CoA.
4) Which of the following would slow down or inhibit key enzymes of Krebs cycle and glycolysis?
A) Excess amount of ADP and Pi
B) Limited amount of ATP
C) Excess amount of NAD+.
D) Excess amount of citrate.
E) Limited amount of FADH2.
5) How many moles of NADH and FADH2 will be made for each mole of sucrose (Table sugar, a
disaccharide) that goes through glycolysis, acetyl CoA formation and Krebs cycle?
A) 2 NADH and 1 FADH2
B) 5 NADH and 1 FADH2
C) 10 NADH and 2 FADH2
D) 20 NADH and 4 FADH2
E) 40 NADH and 8 FADH2
B. Short Answer Questions
The Figure given below shows the details of acetyl CoA formation from pyruvate, which occurs
prior to Krebs cycle and the detailed steps and enzymes in Krebs cycle.
1. List the net inputs and outputs of Krebs cycle and write where the inputs come from and
the outputs go to in a Table form.
2. Circle the first committed step and the rate limiting steps of Krebs cycle and the names of
the enzymes catalyzing these steps. Name one activator and one inhibitor of these
enzymes involved in regulation of their activity?