Question 1

Amylo pectinosis is caused due to absence of?

Accepted Answer

Answer reason: Amylopectinosis (Andersen disease, GSD type IV) results from deficiency of the glycogen branching enzyme (amylo-1,4 to 1,6-transglucosidase). Debranching enzyme, acid maltase, and glucose-6-phosphatase deficiencies cause other GSDs.

Question 2

Her’s disease is characterized by deficiency of?

Accepted Answer

Answer reason: Hers disease (GSD type VI) results from deficiency of hepatic glycogen phosphorylase, the enzyme that releases glucose-1-phosphate from liver glycogen.

Question 3

Tarui disease is characterized by the deficiency of the enzyme?

Accepted Answer

Answer reason: Tarui disease (glycogen storage disease type VII) is due to deficiency of phosphofructokinase in muscle and erythrocytes. Liver phosphorylase (Hers), muscle phosphorylase (McArdle), and lysosomal acid maltase (Pompe) are different GSDs.

Question 4

Isoenzymes can be characterized by?

Accepted Answer

Answer reason: Isoenzymes are different molecular forms of an enzyme that are structurally distinct but perform the same catalytic function. Among the options, the one describing similar enzymes (D) best matches this concept, whereas the others describe cofactors/zymogens or enzymes with identical structure.

Question 5

Which of the following statement is correct about denaturation?

Accepted Answer

Answer reason: Protein denaturation disrupts secondary/tertiary structure by breaking noncovalent interactions, especially hydrogen bonds; it does not cleave peptide bonds or remove terminal groups.

Question 6

How many ATPs are produced in the conversion of phosphoenol pyruvate to citrate?

Accepted Answer

Answer reason: PEP to pyruvate via pyruvate kinase yields 1 ATP; pyruvate to acetyl‑CoA via PDH generates 1 NADH (~3 ATP, classical yield); combining acetyl‑CoA with oxaloacetate to form citrate yields no ATP. Total = 1 + 3 = 4 ATP.

Question 7

Which one of the following is a rate limiting enzyme of gluconeogenesis.....?

Accepted Answer

Answer reason: Among the options, only pyruvate carboxylase is a key regulatory enzyme of gluconeogenesis (pyruvate to oxaloacetate). The others are glycolytic enzymes.

Question 8

The glycolysis is regulated by?

Accepted Answer

Answer reason: Key regulatory steps of glycolysis are catalyzed by hexokinase, phosphofructokinase-1, and pyruvate kinase; therefore all listed enzymes regulate glycolysis.

Question 9

Benedict's test is less likely to give weakly positive results with concentrated urine due to the action of?

Accepted Answer

Answer reason: Concentrated urine can give a weak positive Benedict’s test because uric acid in urine acts as a reducing agent, reducing cupric ions to cuprous oxide.

Question 10

The sequence of reaction converting glucose into pyruvate and lactate with production of ATPs?

Accepted Answer

Answer reason: Glycolysis is the metabolic pathway that breaks down glucose to pyruvate, producing ATP; under anaerobic conditions pyruvate is reduced to lactate.

Question 11

The Fischer projection is a three-dimensional representation of a three-dimensional organic molecule by projection?

Accepted Answer

Answer reason: A Fischer projection is a two-dimensional representation used to depict the 3D stereochemistry of molecules (e.g., carbohydrates). Therefore the statement claiming it is a three-dimensional representation is false.

Question 12

Which of the following is not reducing sugar...?

Accepted Answer

Answer reason: Sucrose is a non-reducing sugar because both anomeric carbons are tied up in an α1→β2 glycosidic bond, leaving no free anomeric carbon. Lactose, maltose, and fructose are reducing sugars.

Question 13

The increase of second messengers’ (cAMP, cGMP, Ca2+ etc.) concentration leads to?

Accepted Answer

Answer reason: Second messengers such as cAMP, cGMP, and Ca2+ activate specific protein kinases (e.g., PKA, PKG, Ca2+/calmodulin-dependent kinases), leading to phosphorylation of target proteins.

Question 14

Α-D-glucose and β-D-glucose are?

Accepted Answer

Answer reason: Α- and β-D-glucose differ in configuration only at the anomeric (C1) carbon formed during cyclization, making them anomers.

Question 15

Which of the following is a reducing sugar?

Accepted Answer

Answer reason: Isomaltose (α-1,6 glucose-glucose) retains a free anomeric carbon and can act as a reducing sugar. Sucrose and trehalose have glycosidic bonds between both anomeric carbons (nonreducing), and agar is a nonreducing polysaccharide.

Question 16

Sucrose consists of?

Accepted Answer

Answer reason: Sucrose is a disaccharide composed of glucose and fructose linked by an α1–β2 glycosidic bond.

Question 17

Which of the following is a non-reducing sugar?

Accepted Answer

Answer reason: Trehalose is a non-reducing disaccharide because both anomeric carbons are involved in an α,α-1,1 linkage, leaving no free hemiacetal. Isomaltose, maltose, and lactose have a free anomeric carbon and are reducing sugars.

Question 18

Osazones are not formed with the?

Accepted Answer

Answer reason: Osazone formation requires a free reducing carbonyl group. Sucrose is a non-reducing disaccharide because both anomeric carbons are involved in the glycosidic bond, so it does not form osazones.

Question 19

Which of the following is not an enzyme involved in glycolysis?

Accepted Answer

Answer reason: Enolase (spelled here as Euolase), aldolase, and hexokinase are glycolytic enzymes; glucose oxidase is not part of glycolysis.

Question 20

Polysaccharides ...?

Accepted Answer

Answer reason: All statements describe polysaccharides: they are polymers of many monosaccharides, serve storage (starch, glycogen) and structural roles (cellulose), and occur abundantly in connective tissue as glycosaminoglycans.

Question 21

All the following are sulphur containing amino acids found in proteins except?

Accepted Answer

Answer reason: Cysteine and methionine contain sulfur, and cystine is the disulfide-linked form of cysteine present in proteins. Threonine is a hydroxy amino acid and does not contain sulfur.

Question 22

Sulphur containing amino acid is?

Accepted Answer

Answer reason: Sulfur-containing amino acids are methionine and cysteine; among the options only methionine contains sulfur. Leucine and valine are branched-chain amino acids without sulfur, and asparagine is an amide without sulfur.

Question 23

Α-Helix is formed by?

Accepted Answer

Answer reason: The alpha-helix secondary structure of proteins is stabilized by intrachain hydrogen bonds between the carbonyl oxygen of one residue and the amide hydrogen four residues ahead; hydrophobic, electrostatic, and disulfide interactions mainly stabilize tertiary or quaternary structure.

Question 24

A nucleoside consists of?

Accepted Answer

Answer reason: A nucleoside is composed of a nitrogenous base linked to a pentose sugar; it does not include phosphate.

Question 25

A nucleotide consists of?

Accepted Answer

Answer reason: A nucleotide is composed of a nitrogenous base (purine or pyrimidine), a sugar, and a phosphate group; only option B includes all three components.

Question 26

The sugar moiety present in DNA is?

Accepted Answer

Answer reason: DNA contains the pentose sugar deoxyribose; ribose is in RNA, and lyxose/ribulose are not components of DNA.

Question 27

The sugar moiety present in RNA is?

Accepted Answer

Answer reason: RNA contains D-ribose as its pentose sugar; DNA contains 2-deoxyribose. Ribulose and arabinose are not components of RNA.

Question 28

The nitrogenous base present in the RNA molecule is?

Accepted Answer

Answer reason: RNA contains uracil instead of thymine; xanthine and hypoxanthine are not standard bases in RNA.

Question 29

Milk sugar is known as?

Accepted Answer

Answer reason: Milk sugar is the disaccharide lactose (glucose + galactose).

Question 30

Prostaglandins are synthesized in the body from?

Accepted Answer

Answer reason: Prostaglandins are eicosanoids produced from arachidonic acid via the cyclooxygenase pathway.

Question 31

Prostaglandins have a common structure based on prostanoic acid which contains carbon atoms?

Accepted Answer

Answer reason: Prostaglandins are eicosanoids derived from a 20‑carbon prostanoic acid skeleton.

Question 32

Arachidonic acid contains the number of double bonds?

Accepted Answer

Answer reason: Arachidonic acid is designated 20:4 (ω-6), indicating four double bonds.

Question 33

What are short polypeptides called?

Accepted Answer

Answer reason: Short chains of amino acids (few residues) are termed oligopeptides; primary and secondary refer to levels of protein structure, not chain length.

Question 34

What is comprised of alpha-helices or parallel or antiparallel beta-pleated sheets?

Accepted Answer

Answer reason: Alpha-helices and beta-pleated sheets are the classic elements of protein secondary structure stabilized by hydrogen bonding.

Question 35

At what amino acids can beta-turns occur?

Accepted Answer

Answer reason: Beta-turns commonly occur at residues that facilitate tight turns: proline introduces a kink due to its rigid cyclic structure, and glycine is small and flexible, accommodating the turn.

Question 36

Where can disulfide covalent linkages occur between adjacent alpha-helices?

Accepted Answer

Answer reason: Keratin is a coiled-coil protein rich in cysteine; disulfide bonds form between adjacent alpha-helices and provide strength. Hair and nails are composed largely of keratin, so all listed locations apply.

Question 37

Fats and oils are also known as _______?

Accepted Answer

Answer reason: Dietary fats and oils are triacylglycerols (triglycerides): glycerol esterified with three fatty acids. The other options refer to peptides, polymers in general, or carbohydrates.

Question 38

What is the relationship between glucose, mannose and galactose?

Accepted Answer

Answer reason: Glucose, mannose, and galactose are aldohexoses where mannose differs from glucose at C-2 and galactose differs at C-4; thus they are epimers of glucose.

Question 39

What is used to identify reducing sugars and in the past was used to test for diabetes mellitus?

Accepted Answer

Answer reason: Benedict's reagent detects reducing sugars by reducing Cu2+ to Cu2O, producing a color precipitate; it was historically used to detect glycosuria in diabetes.

Question 40

NAD+ is a ____________, its reduced form is ______________?

Accepted Answer

Answer reason: NAD+ is an oxidized electron carrier that accepts electrons and a proton to become NADH; NADPH is a different cofactor used in anabolic pathways.

Question 41

How many molecules of carbon dioxide are generated for each molecule of acetyl CoA introduced into the citric acid cycle?

Accepted Answer

Answer reason: In the TCA cycle, each acetyl-CoA undergoes two oxidative decarboxylations (at isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase), releasing two CO2.

Question 42

In electrophoresis, the best support medium to use because it is thermostable, strong, transparent, and eliminates endosmosis due to the lack of a charge is?

Accepted Answer

Answer reason: Polyacrylamide gels are uncharged, mechanically strong, transparent, and thermostable, which minimizes electroendosmosis. Agar/agarose and cellulose acetate carry residual charges and are less ideal for eliminating endosmosis.

Question 43

The component of an electrophoresis system that carries the applied current and establishes the pH at which electrophoresis is performed is the?

Accepted Answer

Answer reason: In electrophoresis, the buffer solution conducts electric current and sets the system pH; the power supply provides voltage, the support medium is the gel, and the stain only visualizes bands.

Question 44

Which molecule serves as the primary “energy currency” of the cell?

Accepted Answer

Answer reason: Adenosine triphosphate (ATP) stores and transfers energy for nearly all cellular processes. The breaking of high-energy phosphate bonds releases usable energy for metabolic reactions, making ATP the essential “energy currency” of the cell.

Question 45

Which vitamin acts as a coenzyme for transamination reactions?

Accepted Answer

Answer reason: Vitamin B6 (pyridoxine), in the form of pyridoxal phosphate, serves as an essential coenzyme in transamination reactions, which are critical for amino acid metabolism and synthesis.

Question 46

Which of the following substances is classified as a carbohydrate?

Accepted Answer

Answer reason: Glucose is a monosaccharide carbohydrate used as a primary energy source in cellular metabolism.

Question 47

Which vitamin acts as a coenzyme in transamination reactions?

Accepted Answer

Answer reason: Pyridoxal phosphate, the active form of vitamin B6, is essential for aminotransferase activity, enabling amino group transfer in metabolic pathways.

Question 48

Which of the following produces pyruvate?

Accepted Answer

Answer reason: Alanine undergoes transamination via alanine aminotransferase to form pyruvate, entering gluconeogenesis or the TCA cycle. Leucine and lysine are strictly ketogenic and degrade to acetoacetyl-CoA/acetyl-CoA, not pyruvate. Isoleucine yields acetyl-CoA and succinyl-CoA. Therefore, alanine is the amino acid that produces pyruvate.

Question 49

An acid present in proteins is?

Accepted Answer

Answer reason: Proteins are polymers of amino acids, each containing both an amino group and a carboxylic acid group. Thus the characteristic acids associated with protein structure are amino acids. Lactic acid is a metabolic byproduct of anaerobic glycolysis, and propanoic and palmitic acids are fatty acids related to lipids, not protein building blocks.

Question 50

Ketone bodies are synthesised in?

Accepted Answer

Answer reason: Ketone bodies are produced primarily in the liver mitochondria during fasting and uncontrolled diabetes from acetyl-CoA generated by fatty acid beta-oxidation. The liver uniquely expresses mitochondrial HMG-CoA synthase and HMG-CoA lyase required for ketogenesis. Brain and muscle lack the full enzymatic pathway and primarily utilize, not synthesize, ketone bodies. Although kidneys may have minor capacity, the principal and clinically relevant site is the liver.

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