Where are the enzymes of the citric acid cycle primarily situated?
Answer
(A)
The central region of mitochondria
2
What is the first reaction in the citric acid cycle?
Answer
(B)
Combining acetyl-CoA with oxaloacetate
3
Which molecule acts as a catalyst in the citric acid cycle?
Answer
(A)
Oxaloacetate
4
Which citric acid cycle enzyme can also be found outside the mitochondria?
Answer
(C)
a-Ketoglutarate dehydrogenase
5
What is necessary for the α-ketoglutarate dehydrogenase enzyme to function in the citric acid cycle?
Answer
(A)
NAD
6
Assuming a solution contains all citric acid cycle components, excess acetyl-CoA, and is at the right pH, which factor would limit the cycle's speed?
Answer
(D)
Cofactor reduction
7
In the TCA cycle, what enzyme changes oxalosuccinate into α-ketoglutarate?
Answer
(B)
Isocitrate dehydrogenase
8
Which cofactor is essential for the enzyme -ketoglutarate dehydrogenase in the citric acid cycle?
Answer
(A)
Lipoate
9
In the citric acid cycle, which reaction produces a high-energy phosphate through substrate-level phosphorylation?
Answer
(D)
Succinyl CoA ⇌†† α-Succinate
10
Fluoroacetate prevents which reaction in the citric acid cycle?
Answer
(C)
Citrate ⇌†† α-cis-aconitate
11
What substance inhibits the conversion of α-Ketoglutarate into succinyl-CoA?
Answer
(B)
Arsenite
12
How many ATP molecules are produced in a single cycle of the citric acid cycle?
Answer
(B)
12
13
What is the net ATP yield from the complete oxidation of one glucose molecule?
Answer
(D)
38 ATP
14
Which metabolic intermediate can serve as both a starting material and an end product in glucose metabolism?
Answer
(A)
Lactate
15
Which of the following molecules can freely pass through the mitochondrial membrane?
Answer
(B)
Malate
16
Which reaction in the Kreb's cycle does not require a cofactor from the vitamin B group?
Answer
(A)
Citrate ‡† isocitrate
17
Which coenzyme is NOT used in the formation of acetyl-CoA from pyruvate?
Answer
(B)
Biotin
18
In the citric acid cycle, which molecule acts as a carrier?
Answer
(C)
Oxaloacetate
19
Which substance specifically inhibits succinate dehydrogenase?
Answer
(B)
Arsenite
20
Which enzyme in the citric acid cycle is regulated by allosteric control?
Answer
(C)
Fumarase
21
What is the net ATP production from the Rapport-Leubering pathway in red blood cells?
Answer
(A)
0
22
Under aerobic versus anaerobic conditions, what is the approximate ratio of net ATP molecules formed per glucose molecule?
Answer
(C)
18:1
23
Glycogen synthesis utilizes a specific nucleotide of glucose. In the following reaction, what does NuDP represent? NuDP Glucose + glycogen,→ NuDP + glycogen+1
Answer
(C)
UDP
24
Which describes the state of the enzyme phosphoglucomutase during the conversion of glucose 6-phosphate to glucose 1-phosphate?
Answer
(D)
Phosphorylated-dephosphorylatedrephosphorylated
25
Approximately what percentage of the liver's weight is glycogen?
Answer
(A)
6%
26
Which enzyme creates branch points during glycogenesis?
Answer
(A)
Amylo [1→ 4] [1→ 6] transglucosidase
27
In glycogenolysis, which enzyme facilitates the transfer of a trisaccharide unit, exposing a 1→6 branch point?
Answer
(B)
α-[14] α-[14] Glucan transferase
28
Which step in the synthesis of glycogen from glucose is reversible?
Answer
(B)
Glucose 6-phosphate glucose 1-phosphate
29
In which of the following tissues is the enzyme glucose-6-phosphatase, which converts glucose 6-phosphate to glucose, not present?
Answer
(B)
Muscle
30
Which molecule acts as an allosteric activator of glycogen synthase?
Answer
(B)
Glucose-6-Phosphate
31
Which factor suppresses the function of glycogen synthase?
Answer
(C)
Mg2+
32
Which hormone stimulates glycogen synthase function?
Answer
(A)
Insulin
33
What are the distinguishing traits of an active site?
Answer
(D)
Both (A) and (B)
34
A deficiency in which enzyme defines Von Gierke's disease?
Answer
(A)
Glucose-6-phosphatase
35
What enzyme's absence causes Cori disease (Limit dextrinosis)?
Answer
(B)
Debranching enzyme
36
Mc Ardle's syndrome is caused by the lack of which enzyme?
Answer
(B)
Muscle phosphorylase
37
Which enzyme deficiency is associated with Pompe's disease?
Answer
(A)
Lysosomal α-1→4 and 1→6-glucosidase
38
What enzyme deficiency results in Amylopectinosis?
Answer
(B)
Branching enzyme
39
What enzyme is deficient in Her's disease?
Answer
(B)
Liver phosphorylase
40
Tarui disease is linked to the lack of which enzyme?
Answer
(C)
Muscle and erythrocyte phosphofructokinase
41
Which enzyme is involved in the hexose monophosphate pathway?
Answer
(D)
Glucose-6-phosphate dehydrogenase
42
Which molecule accepts hydrogen in the pentose phosphate pathway?
Answer
(B)
NADP
43
Where are the enzymes of the pentose phosphate pathway located?
Answer
(A)
Cytosol
44
What enzyme converts D-ribulose-5-phosphate to D-ribose-5-phosphate in the pentose phosphate pathway?
Answer
(B)
Ketoisomerase
45
Which B vitamin is required by the transketolase enzyme in the pentose phosphate pathway?
Answer
(B)
Thiamin
46
In a reaction, Xylulose-5-phosphate donates active glycolaldehyde. Which molecule acts as the acceptor?
Answer
(A)
Erythrose 4-phosphate
47
What is a significant product generated by the pentose phosphate pathway?
Answer
(A)
NADPH for reductive synthesis
48
The pentose phosphate pathway helps protect erythrocytes from hemolysis by supporting which enzyme?
Answer
(C)
Glutathionic peroxidase
49
What enzyme deficiency in the pentose phosphate pathway is often associated with hemolytic anemia?
