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Cell Biology Multiple Choice Questions on “Aerobic Respiration – Oxidative Metabolism”.
1. Which of the following molecules is present in the mitochondrion?
A. Acetyl CoA
B. Acetyl CoB
C. Acetylanase
D. Acetylcholine
Answer: A
Clarification: Acetyl CoA is present in the mitochondrion which binds with the pyruvate and undergoes the TCA cycle. 2 ATP molecules are generated for one molecule of oxygen; as a result of mitochondrial metabolism.
2. The enzymes of glycolysis are located in the ______________
A. mitochondria
B. golgi complex
C. cytosol
D. cytoplasm
Answer: C
Clarification: Cytosol is the fluid part of the cytoplasm. Starting with the glucose, the initial steps of oxidation process are carried out by the enzymes of glycolysis.
3. How many reactions are constituted in a glycolytic pathway?
A. 2
B. 5
C. 10
D. 15
Answer: C
Clarification: A total of 10 reactions are present in a glycolytic pathway. The first step is phosphorylation of glucose at the expense of one adenosine triphosphate molecule.
4. At the expense of two ATP molecules, how many phosphate groups are present on the fructose in the third step of glycolysis?
A. 2
B. 3
C. 4
D. 5
Answer: A
Clarification: Glucose is first phosphorylated at the expense of one ATP molecule, rearranging to form fructose phosphate and then phosphorylation takes place again leading to a total of two phosphate groups attached to the fructose chain.
5. How many molecules of ATP are formed per molecule of glucose oxidized?
A. 1
B. 2
C. 3
D. 4
Answer: B
Clarification: Two ATP molecules are formed per molecule of glucose oxidized. Along with ATP, in the net reaction two pyruvate molecules and two molecules of water are also formed.
6. Most of the free energy present in the glucose is stored as ATP after glycolysis.
A. True
B. False
Answer: B
Clarification: Only a small fraction of free energy available in glucose is available to cell for the net synthesis of two ATP molecules during glycolysis. Most of the energy is stored in pyruvate.
7. In presence of oxygen, how many additional molecules of ATP can be formed by metabolizing pyruvate and NADH in the mitochondria?
A. more than 20
B. more than 30
C. more than 50
D. more than 100
Answer: B
Clarification: The end products of glycolysis, pyruvate and NADH can be metabolized in the mitochondria in presence of oxygen. This process can generate more than 30 additional molecules of ATP.
8. Decarboxylation of pyruvate group takes place in the ________________
A. outer mitochondrial membrane
B. inner mitochondrial membrane
C. mitochondrial matrix
D. cytosol
Answer: D
Clarification: In the process of extracting energy from the pyruvate, the molecule is transported to the inner mitochondrial membrane and then to the matrix where it is decarboxylated to form a two-carbon acetyl group.
9. Coenzyme A is derived from _________________
A. thiamin
B. riboflavin
C. pantothenic acid
D. biotin
Answer: C
Clarification: Coenzyme A is an organic compound derived from pantothenic acid. Pantothenic acid is a B-group vitamin and is water soluble. The acetyl group from the decarboxylation of pyruvate is transferred to coenzyme A, making it acetyl CoA.