Question 1
A cell’s reservoir of NADPH represents its _______________
A. oxidation state
B. oxidation power
C. tensile strength
D. reducing power
View Answer
Answer: Option D
Explanation:
A cell’s reservoir of NADPH is a measure of its reducing power and the usable energy. NADPH is a compound similar to NADH but with an additional phosphate group.
Question 2
Anabolic pathways are energy-requiring.
A. True
B. False
View Answer
Answer: Option A
Explanation:
Anabolic pathways lead to the formation of complex molecules from simpler raw products. These require chemical energy which is supplied by the exergonic catabolic pathways.
Question 3
Catabolic pathways result in _______________ of the molecules.
A. assembly
B. functionalization
C. conformation
D. disassembly
View Answer
Answer: Option D
Explanation:
Catabolism refers to the disassembly of complex molecules to form simpler products. Catabolism hence serves two roles: providing raw materials for synthesis of products and making chemical energy available for survival of a cell.
Question 4
Energy released by catabolic pathways is stored in how many forms?
A. 1
B. 2
C. 3
D. 4
View Answer
Answer: Option B
Explanation:
Energy released by catabolic pathways is stored primarily in two forms: high energy phosphates like adenosine triphosphate and high energy electrons (NADPH).
Question 5
Glycolysis begins with which of the following reactions?
A. reduction
B. oxidation
C. phosphorylation
D. acidification
View Answer
Answer: Option C
Explanation:
Glycolysis begins with the addition of a sugar molecule to a phosphate group. Phosphorylation activates the sugar molecule to take part in later steps of the process and also reduce the concentration of glucose in the cytoplasm, promoting continued diffusion from blood to the cell.
Question 6
How many mechanisms exist for altering the shape of an enzyme, playing a role in regulating glucose oxidation?
A. 1
B. 2
C. 3
D. 4
View Answer
Answer: Option B
Explanation:
For regulating glucose oxidation, there are two mechanisms that are responsible for altering the shape of an enzyme’s active site namely covalent modification and allosteric modification.
Question 7
How many molecules of ATP are formed per molecule of oxidation of glucose?
A. 12
B. 24
C. 36
D. 48
View Answer
Answer: Option C
Explanation:
In one cycle of glycolysis, 6 ATP is obtained. Each molecule of glucose gives 2 pyruvate which corresponds to 6 ATP. There is also formation of 2 acetyl-CoA molecules which is about 24 ATP. Thus each molecule of Glucose give 36 ATP. ( Note that about 34 ATP molecules are consumed in glycolysis thus the net yield is 2 ATP).
Question 8
How many types of protein kinases are there?
A. 1
B. 2
C. 3
D. 4
View Answer
Answer: Option B
Explanation:
There are two types of protein kinases: one adds phosphate group to tyrosine residues in a protein and the other adds phosphate group to serine or threonine residues.
Question 9
In case of repeated contraction, muscle cells regenerate NAD⁺ by converting pyruvate to _____________
A. glycogen
B. lactate
C. starch
D. cellulose
View Answer
Answer: Option B
Explanation:
In case of repeated contraction, the oxygen levels drop down and make it difficult to keep up with the cell’s metabolic demands. Under these conditions, skeletal muscle cells regenerate NAD⁺ by converting pyruvate to lactate.
Question 10
In fermentation, which of the following is regenerated?
A. Starch
B. Oxygen
C. NAD⁺
D. NADH
View Answer
Answer: Option C
Explanation:
Cells are able to regenerate NAD⁺ by fermentation. In this process the transfer of electrons take place from NADH to pyruvate or to a compound derived from pyruvate.
Question 11
NAD is a _________
A. enzyme
B. cofactor
C. protein
D. nucleoside
View Answer
Answer: Option B
Explanation:
Nicotinamide adenine dinucleotide is a non-protein cofactor called coenzyme. NAD plays a key role in the metabolism of the cell by donating and accepting electrons.
Question 12
NAD⁺ can be derived from which vitamin?
A. A
B. C
C. Riboflavin
D. Niacin
View Answer
Answer: Option D
Explanation:
NAD⁺ is the reduced state of the coenzyme NAD. It is derived from the vitamin niacin and is loosely bound to the enzyme dehydrogenase.
Question 13
Protein kinases are responsible for transferring which group?
A. oxygen
B. carbon
C. amino
D. phosphate
View Answer
Answer: Option D
Explanation:
Protein kinases are a class of enzymes that transfer phosphate group to other proteins (covalent modification). These are hence vital in hormone action, cell division and gene expression.
Question 14
The TCA cycle occurs in which region of a prokaryotic cell?
A. cytosol
B. mitochondria
C. ribsomes
D. golgi complex
View Answer
Answer: Option A
Explanation:
There are two stages in the catabolism of glucose namely glycolysis which occurs in the cytosol and tricarboxylic acid (TCA) cycle which occurs in the cytosol of prokaryotes and mitochondria of eukaryotes.
Question 15
Yeast cells convert pyruvate to lactate.
A. True
B. False
View Answer
Answer: Option B
Explanation:
Unlike the cells of skeletal muscles, which convert pyruvate to lactate in case of low oxygen supply; the yeast cells convert pyruvate to ethanol.
Question 16
Chemical compounds involved in the process of metabolism is known as ___________
A. Metabolites
B. Radicals
C. Catabolites
D. Intermediates
View Answer
Answer: Option A
Explanation:
Metabolites are the chemical compounds which take part in the process of metabolism. Metabolism involves discrete pathways which proceed in a stepwise manner and transform substrate to end product.
Question 17
In which of the following phenomenon the end product act as co-repressor and repress the synthesis of metabolic enzymes?
A. Allosteric regulation
B. Feedback repression
C. Feedback inhibition
D. Regulation by phosphorylation
View Answer
Answer: Option B
Explanation:
Feedback repression is different from feedback inhibition, here the end product of the pathway acts as a co-repressor and represses the synthesis of an enzyme which is required at the earlier stage of the pathway.
Question 18
Name the inhibition where end products of biosynthesis pathway inhibit the activity of the first enzyme?
A. Feedback inhibition
B. Feedback repression
C. Allosteric inhibition
D. Competitive inhibition
View Answer
Answer: Option A
Explanation:
Feedback inhibition is also known as end-product inhibition, the unique feature in this is the inhibition of the first enzyme in a biosynthetic pathway by the end product which in turn control its production.
Question 19
Name the type of the pathway which is involved in the synthesis of compounds?
A. Anabolic pathways
B. Catabolic pathways
C. Amphibolic pathway
D. Anapleurotic pathway
View Answer
Answer: Option A
Explanation:
Anabolic pathway involves the synthesis of compounds, and it is endergonic in nature. This pathway works just opposite to catabolic pathway where molecules are broken down. Amphibolic is a combination of both anabolic and catabolic pathway.
Question 20
Regulation of metabolic pathway is done by following ways except one, mark the one?
A. Substrate concentration
B. Allosteric regulation of enzymes
C. Availability of oxygen
D. Extracellular signals i.e. hormones or growth factors
View Answer
Answer: Option C
Explanation:
Metabolic pathways depend on the substrate concentration as well as extracellular signals. Coenzymes or certain metabolic intermediate also regulate the metabolism while not all the metabolic pathways depend on the oxygen. Oxygen is required only for aerobic reactions.
Question 21
The catabolic pathway is exergonic in nature.
A. True
B. False
View Answer
Answer: Option A
Explanation:
Catabolic pathway is the type of a metabolic pathway in which oxidative breakdown of larger complex molecules generates a huge amount of energy. Releasing energy is exergonic process while consuming energy is an endergonic process which can be seen in an anabolic pathway.
Question 22
Which of the following cycle shows amphibolic pathway?
A. Glyoxylate
B. Citric acid cycle
C. Glycolysis
D. Lipid metabolism
View Answer
Answer: Option B
Explanation:
Amphibolic pathway combines both anabolic and catabolic pathway, it acts as a link or ‘crossroad’ between the two pathways. The amphibolic pathway can be seen in the citric acid cycle.
Question 23
Which of the following is not an enzyme-catalyzed reaction in metabolism?
A. Isomerization and elimination
B. Internal rearrangement
C. Maillard reaction
D. Free radical reaction
View Answer
Answer: Option C
Explanation:
Metabolic reactions fall into five categories: group transfer, making or breaking carbon bonds, internal rearrangement, free radical reactions, and isomerizations while the Maillard reaction is a non-enzymatic reaction in which amino group-containing compounds react with sugar molecules.
Question 24
Which of the following has a spiral metabolic pathway?
A. Glycolysis
B. Citric acid cycle
C. Glyoxylate cycle
D. Fatty acid biosynthesis
View Answer
Answer: Option D
Explanation:
Metabolism involves the generation of energy and synthesis of biological molecules. It can follow several paths like a spiral pathway for fatty acid synthesis, the linear pathway for glycolysis, and cyclic pathway for the citric acid cycle.