Question 1

Mucopolysaccharides are?

Accepted Answer

Answer reason: Mucopolysaccharides (glycosaminoglycans) consist of repeating disaccharide units containing amino sugars and uronic acids; thus they are heteropolysaccharides, not proteins or amino acids.

Question 2

Which one of the following is semi-essential amino acid for humans?

Accepted Answer

Answer reason: Arginine is considered a semi-essential (conditionally essential) amino acid in humans, especially during growth and stress; valine and lysine are essential, while tyrosine is generally nonessential.

Question 3

A Lipotropic factor is?

Accepted Answer

Answer reason: Choline acts as a lipotropic factor by mobilizing hepatic fat and preventing fatty liver; the other options are not lipotropic agents.

Question 4

Tissues form lactic acid from glucose. This phenomenon is termed as?

Accepted Answer

Answer reason: Lactic acid is produced when pyruvate from glycolysis is reduced under low-oxygen conditions; this is anaerobic glycolysis, not aerobic pathways or oxidative phosphorylation.

Question 5

Catalyses the reaction in group added to double bond converted into single bond?

Accepted Answer

Answer reason: Lyases catalyze addition of groups to double bonds (or removal to form double bonds). Adding a group converts a double bond to a single bond, so the enzyme class is lyases.

Question 6

What test would you perform on potatoes to identify starch?

Accepted Answer

Answer reason: Iodine reacts with starch to produce a blue-black color. Benedict’s and Fehling’s tests detect reducing sugars, and litmus paper tests pH.

Question 7

The break down of glucose by enzymes, giving energy and pyruvic acid is called ________?

Accepted Answer

Answer reason: Glycolysis is the enzymatic breakdown of glucose to pyruvate with the production of ATP. The other options refer to glucose or glycogen synthesis or glycogen breakdown.

Question 8

Fibrous protein such as silk fibroin consists of polypeptide chains arranged in?

Accepted Answer

Answer reason: Silk fibroin is a fibrous protein whose polypeptide chains form antiparallel β-pleated sheets due to repetitive Gly-Ala/Ser sequences, not α-helix or β-helix.

Question 9

NAD is required as a coenzyme in?

Accepted Answer

Answer reason: NAD+ serves as an electron acceptor for several dehydrogenases in the citric acid cycle and in β-oxidation (e.g., β-hydroxyacyl-CoA dehydrogenase). The HMP shunt uses NADP+/NADPH, not NAD+.

Question 10

Biotin is required as a coenzyme by?

Accepted Answer

Answer reason: Biotin (vitamin B7) functions as a CO2 carrier for carboxylase enzymes, e.g., pyruvate carboxylase and acetyl-CoA carboxylase; it is not a coenzyme for dehydrogenases or decarboxylases.

Question 11

Biotin is a coenzyme for?

Accepted Answer

Answer reason: Biotin serves as a CO2 carrier for carboxylase enzymes, including pyruvate carboxylase, acetyl-CoA carboxylase, and propionyl-CoA carboxylase; therefore, all listed are correct.

Question 12

Two sugars which differ from one another only in configuration around a single carbon atom are termed?

Accepted Answer

Answer reason: Epimers are stereoisomers that differ in configuration at only one chiral carbon. Anomers differ specifically at the anomeric carbon; optical isomers and stereoisomers are broader terms.

Question 13

In which of the following types of enzyme water may be added to a C-C resulting breaking the bond?

Accepted Answer

Answer reason: Hydratases catalyze hydration across a carbon–carbon double bond, adding H and OH and thereby breaking the C=C into a single C–C bond. The other enzymes perform hydrolysis, hydroxylation, or oxygen incorporation reactions.

Question 14

Endopeptidases are those enzymes which cleave the polypeptide at?

Accepted Answer

Answer reason: Endopeptidases hydrolyze peptide bonds within a polypeptide chain, not at the terminal ends; exopeptidases remove residues from the N- or C-terminus.

Question 15

An aromatic amino acid is?

Accepted Answer

Answer reason: Among the options, only tyrosine contains an aromatic ring; lysine and arginine are basic aliphatic amino acids and taurine is not a standard aromatic amino acid.

Question 16

The amino acid with a nonpolar side chain is?

Accepted Answer

Answer reason: Valine is a nonpolar aliphatic amino acid; serine, threonine, and asparagine have polar side chains.

Question 17

The basic amino acids are?

Accepted Answer

Answer reason: Lysine has a positively charged side chain at physiological pH, classifying it as a basic amino acid. Glycine and alanine are neutral, and bile acids are not amino acids.

Question 18

According to Bronsted, acids are?

Accepted Answer

Answer reason: By Brønsted–Lowry theory, an acid donates a proton (H+) and a base accepts a proton.

Question 19

What is the term for the molecule that an enzyme acts upon?

Accepted Answer

Answer reason: Enzymes bind and act on their specific reactant called the substrate, converting it into products.

Question 20

Haemoglobin is a?

Accepted Answer

Answer reason: Hemoglobin is a conjugated globular protein (globin chains plus heme), not a fat, vitamin, or food.

Question 21

Which group of proteins is biologically active?

Accepted Answer

Answer reason: Enzymes are proteins that act as biological catalysts, the classic example of biologically active proteins. Antibodies and some hormones are proteins, but the term most specifically refers to enzymes.

Question 22

What is the term for the total sum of chemical activity in the body?

Accepted Answer

Answer reason: Metabolism encompasses the total of all chemical reactions in the body, including both anabolism and catabolism.

Question 23

Who proposed the fluid mosaic model of the cell membrane?

Accepted Answer

Answer reason: The fluid mosaic model of the cell membrane was proposed by S. J. Singer and G. Nicolson in 1972, describing a lipid bilayer with proteins moving within it.

Question 24

What is the green pigment in leaves and stems of plants that absorbs sunlight for the process of photosynthesis?

Accepted Answer

Answer reason: Chlorophyll is the green pigment that captures light energy for photosynthesis; cellulose is structural, cytoplasm is the cell’s fluid, and glucose is a product of photosynthesis.

Question 25

Which type of bond is present between the two strands of DNA?

Accepted Answer

Answer reason: Complementary bases on the two DNA strands pair via hydrogen bonds (A–T two bonds; G–C three bonds), holding the strands together.

Question 26

Which of the following is a monosaccharide?

Accepted Answer

Answer reason: Glucose is a monosaccharide; sucrose and maltose are disaccharides.

Question 27

Which of the following is not a polyunsaturated fatty acid?

Accepted Answer

Answer reason: Oleic acid is a monounsaturated fatty acid (18:1), whereas linoleic (18:2), linolenic (18:3), and arachidonic acid (20:4) are polyunsaturated.

Question 28

Arachidonic acid in the placenta is synthesized under the influence of which of the following?

Accepted Answer

Answer reason: Phospholipase A2 cleaves membrane phospholipids to release arachidonic acid, the precursor for prostaglandins; estrogen, progesterone, and oxytocin do not synthesize arachidonic acid.

Question 29

Metabolism can be defined as the ________?

Accepted Answer

Answer reason: Metabolism encompasses all anabolic and catabolic chemical reactions occurring in an organism. Other choices describe differentiation, cell replacement, or adaptation/homeostasis.

Question 30

A dipeptide has?

Accepted Answer

Answer reason: A dipeptide is formed by two amino acids joined by a single peptide bond; peptide bonds equal amino acids minus one.

Question 31

Which of the following statements about enzymes or their function is true?

Accepted Answer

Answer reason: All listed statements are correct: enzymes do not change the reaction’s overall free energy (ΔG), they are proteins whose specific 3D conformation determines function, and they catalyze reactions by lowering activation energy.

Question 32

The "lock and key hypothesis" attempts to explain the mechanism of?

Accepted Answer

Answer reason: The lock-and-key model states that an enzyme’s active site is complementary in shape to its specific substrate, explaining enzyme specificity.

Question 33

At high temperature the rate of enzyme action decreases because the increased heat?

Accepted Answer

Answer reason: High temperatures denature enzyme proteins, disrupting tertiary structure and changing the active site so substrates cannot bind effectively, lowering activity. The other options do not explain heat-related loss of enzyme function.

Question 34

The key enzyme in the regulation of fatty acid synthesis is?

Accepted Answer

Answer reason: Acetyl-CoA carboxylase catalyzes the committed rate-limiting step (acetyl-CoA to malonyl-CoA) and is the primary regulatory point of fatty acid synthesis; AMPK and protein phosphatases regulate ACC activity.

Question 35

The isoelectric point of an amino acid is defined as the pH?

Accepted Answer

Answer reason: The isoelectric point (pI) is the pH at which an amino acid has a net zero charge (zwitterion predominates), thus no net migration in an electric field. Options focusing on individual groups or maximum mobility are incorrect.

Question 36

What is the synthesis of large molecules from smaller molecules called?

Accepted Answer

Answer reason: Building complex molecules from simpler ones is anabolism; catabolism breaks down molecules, absorption is uptake, and metabolism encompasses both processes.

Question 37

What are the chief components of a cell?

Accepted Answer

Answer reason: The primary elements that constitute most cellular biomolecules are carbon, hydrogen, oxygen, and nitrogen (CHON).

Question 38

What are the smaller units of protein?

Accepted Answer

Answer reason: Proteins are polymers composed of amino acid monomers linked by peptide bonds. Glycerol is part of fats, glucose is a carbohydrate, and vitamin C is a vitamin.

Question 39

Which of the following amino acids is essential?

Accepted Answer

Answer reason: Valine is an essential branched-chain amino acid; proline, glycine, and tyrosine are nonessential/conditionally essential.

Question 40

Which vitamin is a sulfur-containing vitamin?

Accepted Answer

Answer reason: Biotin (vitamin B7) contains sulfur in its thiophane ring and is commonly identified as the sulfur-containing vitamin among these options.

Question 41

Which type of enzyme inhibitor supports the lock and key hypothesis?

Accepted Answer

Answer reason: Competitive inhibitors resemble the substrate and compete for the enzyme’s active site, fitting like a key in a lock and thus supporting the lock-and-key model.

Question 42

What is an essential feature of a competitive inhibitor?

Accepted Answer

Answer reason: Competitive inhibitors reversibly compete with the substrate for the enzyme’s active site; occupying the active site is their defining property.

Question 43

Compounds having the same structural formula but differing in spatial configuration are known as?

Accepted Answer

Answer reason: Stereoisomers have the same connectivity (structural formula) but differ in three-dimensional arrangement. Anomers, epimers, and optical isomers are specific types of stereoisomers; the general term is stereoisomers.

Question 44

Non essential amino acids?

Accepted Answer

Answer reason: Nonessential amino acids are synthesized by the body; some derive from essential amino acids (e.g., tyrosine from phenylalanine, cysteine from methionine). They are components of proteins and have metabolic roles; synthesis is not limited to diseased states.

Question 45

Histones are?

Accepted Answer

Answer reason: Histones are basic nuclear proteins enriched in the basic amino acids lysine and arginine; they are not identical to protamines, have relatively low molecular weights, and are soluble in water and dilute acids.

Question 46

If the fatty acid is esterified with an alcohol of high molecular weight instead of glycerol, the resulting compound is?

Accepted Answer

Answer reason: Waxes are esters formed from long‑chain fatty acids and long‑chain (high–molecular‑weight) alcohols rather than glycerol. Plasmalogen and cephalin are glycerophospholipids.

Question 47

Lipoic acid is a coenzyme for?

Accepted Answer

Answer reason: Lipoic acid (lipoamide) functions as a swinging-arm coenzyme in multienzyme dehydrogenase complexes, including both pyruvate dehydrogenase and α-ketoglutarate dehydrogenase.

Question 48

Cori disease is caused due to absence of?

Accepted Answer

Answer reason: Cori disease (GSD type III) is due to deficiency of the glycogen debranching enzyme; branching enzyme deficiency causes Andersen disease.

Question 49

Mc Ardle’s syndrome is characterized by the absence of?

Accepted Answer

Answer reason: McArdle disease (glycogen storage disease type V) is due to deficiency of myophosphorylase, the muscle glycogen phosphorylase.

Question 50

Pompe’s disease is caused due to deficiency of?

Accepted Answer

Answer reason: Pompe disease (GSD II) results from deficiency of lysosomal acid α-glucosidase (acid maltase), which cleaves α-1,4 and α-1,6 bonds of glycogen. Other enzymes listed correspond to different disorders (e.g., G6-phosphatase—Von Gierke; PFK—Tarui).

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