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201.

In β-oxidation 3-ketoacyl-CoA is splitted at the 2, 3 position by the enzyme: (A) Hydratase (B) Dehydrogenase (C) Reducatse (D) Thiolase

Answer»

 (D) Thiolase

202.

All the following statements about acetyl CoA carboxylase are true except (A) It is required for de novo synthesis of fatty acids (B) It is required for mitochondrial elongation of fatty acids (C) It is required for microsomal elongation of fatty acids (D) Insulin converts its inactive form into its active form

Answer»

(B) It is required for mitochondrial elongation of fatty acids

203.

The common precursor in the biosynthesis of triacylglycerol and phospholipids is (A) 1, 2-Diacylglycerol phosphate (B) 1-Acylglycerol 3-phosphate (C) Glycerol 3-phosphate (D) Dihydroxyacetone phosphate

Answer»

(A) 1, 2-Diacylglycerol phosphate

204.

In the biosynthesis of triglycerides from glycerol 3-phosphate and acyl-CoA, the first intermediate formed is (A) 2-Monoacylglycerol (B) 1, 2-Diacylglycerol (C) Lysophosphatidic acid (D) Phosphatidic acid

Answer»

(D) Phosphatidic acid

205.

The rate limiting reaction in the lipogenic pathway is (A) Acetyl-CoA carboxylase step (B) Ketoacyl synthase step (C) Ketoacyl reductase step (D) Hydratase step

Answer»

(A) Acetyl-CoA carboxylase step

206.

In the pathway leading to biosynthesis of acetoacetate from acetyl-CoA in liver, the immediate precursor of aceotacetate is (A) Acetoacetyl-CoA (B) 3-Hydroxybutyryl-CoA (C) 3-Hydroxy-3-methyl-glutaryl-CoA (D) 3-Hydroxybutyrate 

Answer»

(A) Acetoacetyl-CoA

207.

The fruit when kept is open, tastes bitter after 2 hours because of (A) Loss of water from juice (B) Decreased concentration of fructose in juice (C) Fermentation by yeast (D) Contamination by bacterial enzymes

Answer»

(D) Contamination by bacterial enzymes

208.

Part of enzyme which combines with nonprotein part to form functional enzyme is (A) Apoenzyme (B) Coenzyme (C) Prosthetic group (D) None of these

Answer»

(C) Prosthetic group

209.

Who got Nobel Prize in 1978 for working on enzymes? (A) Koshland (B) Arber and Nathans (C) Nass and Nass (D) H.G. Khorana

Answer»

(A) Koshland

210.

The enzyme which can add water to a carbon-carbon double bond or remove water to create a double bond without breaking the bond is(A) Hydratase (B) Hydroxylase (C) Hydrolase (D) Esterase

Answer»

(A) Hydratase

211.

An example of lyases is (A) Glutamine synthetase (B) Fumarase (C) Cholinesterase (D) Amylase

Answer»

An example of lyases is Fumarase.

212.

Enzyme catalysed reactions occur in (A) Pico seconds (B) Micro seconds (C) Milli seconds (D) None of these

Answer»

(C) Milli seconds

213.

An organic substance bound to an enzyme and essential for the activity of enzyme is called (A) Holoenzyme (B) Apoenzyme (C) Coenzyme (D) Isoenzyme

Answer»

(C) Coenzyme

214.

Activation or inactivation of certain key regulatory enzymes is accomplished by covalent modification of the amino acid: (A) Tyrosine (B) Phenylalanine (C) Lysine (D) Serine

Answer»

Activation or inactivation of certain key regulatory enzymes is Serine.

215.

The shape of an enzyme and consequently its activity can be reversibly altered from moment to moment by (A) Heat (B) Amino acid substrate (C) Allosteric subunits (D) Sulfur substitutions 

Answer»

(C) Allosteric subunits

216.

On what structural level of the enzyme (primary, secondary, tertiary or quaternary) does the enzymesubstrate interaction depend?

Answer»

The substrate binds to the enzyme in the activation centres. These are specific three-dimensional sites and thus they depend on the protein tertiary and quaternary structures. The primary and secondary structures, however, condition the other structures and so they are equally important.

217.

Which one of the following regulatory actions involves a reversible covalent modification of the enzyme? (A) Phosphorylation of ser-OH on the enzyme (B) Allosteric modulation (C) Competitive inhibition (D) Non-competitive inhibition

Answer» (A) Phosphorylation of ser-OH on the enzyme
218.

How does the formation of the enzyme-substrate complex explain the reduction of the activation energy of chemical reactions? 

Answer»

The enzyme possibly works as a test tube within which reagents meet to form products. With the facilitation of the meeting provided by enzymes, it is easier for collisions between reagents to occur and thus the activation energy of the chemical reaction is reduced. This is one of the possible hypotheses. 

219.

Galactose 1-phosphate is converted to uridine diphosphate galactose, the reaction is catalysed by the enzyme: (A) Glactokinase (B) Galactose 1-phosphate uridyl transferase (C) Uridine diphospho galactose 4-epimerase (D) UDP glucose pyrophosphorylase

Answer»

(B) Galactose 1-phosphate uridyl transferase

220.

An enzyme is a (A) Carbohydrate (B) Lipid (C) Protein (D) Nucleic acid

Answer»

An enzyme is a  Protein.

221.

The Michaehis-Menten hypothesis: (A) Postulates the formation of an enzyme substrate complex (B) Enables us to calculate the isoelectric point of an enzyme (C) States that the rate of a chemical reaction may be independent of substrate concentration (D) States that the reaction rate is proportional to substrate concentration

Answer»

(A) Postulates the formation of an enzyme substrate complex

222.

The activity of HMG-CoA reductase is inhibited by (A) A fungal inhibitor mevastatin (B) Probucol (C) Nicotinic acid (D) Clofibrate

Answer»

(A) A fungal inhibitor mevastatin

223.

HMG-CoA reductase activity is increased by administration of the hormone: (A) Insulin (B) Glucagon (C) Epinephrine (D) Glucocorticoids

Answer»

The Correct option is (A) Insulin

224.

The protein, which is in fact a multifunctional enzyme complex in higher organism is (A) Acetyl transacylase (B) Malonyl transacylase (C) 3-Hydroxy acyl-ACP dehyratase (D) Fatty acid synthase 

Answer»

(D) Fatty acid synthase

225.

The best known cause of galactosemia is the deficiency of (A) Galactose 1-phosphate and uridyl transferase (B) Phosphoglucomutase (C) Galactokinase (D) Lactose synthase

Answer»

(A) Galactose 1-phosphate and uridyl transferase

226.

HMG-CoA is converted to mevalonate by reduction catalysed by (A) HMG-CoA synthetase (B) HMG-CoA reductase (C) Mevalonate kinase (D) Thiolase

Answer»

(B) HMG-CoA reductase

227.

Coenzymes are (A) Heat stable, dialyzable, non protein organic molecules (B) Soluble, colloidal, protein molecules (C) Structural analogue of enzymes (D) Different forms of enzymes

Answer»

(A) Heat stable, dialyzable, non protein organic molecules

228.

In gluconeogensis, an allosteric activator required in the synthesis of oxaloacetate from bicarbonate and pyruvate, which is catalysed by the enzyme pyruvate carboxylase is (A) Acetyl CoA (B) Succinate (C) Isocitrate (D) Citrate

Answer»

(A) Acetyl CoA

229.

The pH optima of most of the enzymes is (A) Between 2 and 4 (B) Between 5 and 9 (C) Between 8 and 12(D) Above 12

Answer»

 (B) Between 5 and 9

230.

The enzyme phosphoenolpyruvate carboxykinase catalyses the conversion of oxaloacetate to phosphoenolpyruvate requires (A) ATP (B) ADP (C) AMP (D) GTP 

Answer»

The Correct option is (D) GTP

231.

In the intestine the rate of absorption is highest for (A) Glucose and galactose (B) Fructose and mannose (C) Fructose and pentose (D) Mannose and pentose

Answer»

(A) Glucose and galactose

232.

Hereditary fructose intolerance involves the absence of the enzyme: (A) Aldalose B (B) Fructokinase (C) Triokinase (D) Phosphotriose isomerase

Answer»

Hereditary fructose intolerance involves the absence of the enzyme Aldalose B.

233.

Amylopectinosis is caused due to absence of (A) Debranching enzyme (B) Branching enzyme (C) Acid maltase (D) Glucose-6-phosphatase

Answer»

Amylopectinosis is caused due to absence of branching enzyme. 

234.

The enzymes of the pentose phosphate pathway are found in the (A) Cytosol (B) Mitochondria (C) Nucleus (D) Endoplasmic reticulum

Answer»

The enzymes of the pentose phosphate pathway are found in the Cytosol.

235.

The substrate for amylase is (A) Cane sugar (B) Starch (C) Lactose (D) Ribose

Answer»

The substrate for amylase is Starch.

236.

The pH optima for lactase is (A) 1.0-2.0 (B) 5.4–6.0 (C) 5.0–7.0 (D) 5.8–6.2

Answer»

The pH optima for lactase is 5.4–6.0.

237.

The ion which activates salivary amylase activity is (A) Chloride (B) Bicarbonate (C) Sodium (D) Potassium

Answer»

(A) Chloride

238.

The pancreatic amylase activity is increased in the presence of (A) Hydrochloric acid (B) Bile salts (C) Thiocyanate ions (D) Calcium ions 

Answer»

(B) Bile salts

239.

The pH optima for pancreatic analyse is (A) 4.0 (B) 7.1 (C) 7.9 (D) 8.6

Answer»

The pH optima for pancreatic analyse is 8.6.

240.

The pH optima for salivary analyse is (A) 6.6–6.8 (B) 2.0–7.5 (C) 7.9 (D) 8.6

Answer»

The pH optima for salivary analyse is  6.6–6.8.

241.

Oxidation of one molecule of glucose yields (A) 12 ATP (B) 24 ATP (C) 38 ATP (D) 48 ATP

Answer»

Oxidation of one molecule of glucose yields 38 ATP.

242.

In citric acid cycle, NAD is reduced in (A) One reactions (B) Two reactions (C) Three reactions (D) Four reactions

Answer»

(C) Three reactions

243.

The number of ATP molecules generated for each turn of the citric acid cycle is (A) 8 (B) 12(C) 24 (D) 38 

Answer»

The number of ATP molecules generated for each turn of the citric acid cycle is 12.

244.

If results of the serum bilirubin, serum ALP, LDH and AST determinations suggest obstructive jaundice, the best confirmatory test would be the estimation of (A) Serum ALT (B) Serum 5’ nucleotidase (C) Serum Pseudo cholinesterase (D) None of these

Answer»

(B) Serum 5’ nucleotidase

245.

Which enzyme estimation will be helpful in differentiating the elevated serum ALP found in obstructive jaundice as well as bone disorders? (A) Serum AST (B) Serum ALT (C) Serum LDH (D) Serum γ-GT

Answer»

(D) Serum γ-GT

246.

The CK isoenzymes present in cardiac muscle is (A) BB and MB (B) MM and MB (C) BB only (D) MB only

Answer»

(B) MM and MB

247.

Serum AST activity is not characteristically elevated as the result of (A) Myocardial infarction (B) Passive congestion of liver (C) Muscular dystrophies (D) Peptic ulcer 

Answer»

(D) Peptic ulcer

248.

The isozyme CK-MB is specifically increased in the blood of patients who had (A) Skeletal muscle disease (B) Recent myocardial infarction (C) Infective hepatitis (D) Myxoedema

Answer»

(B) Recent myocardial infarction

249.

A demonstrable inducer is absent in (A) Allosteric enzyme (B) Constitutive enzyme (C) Inhibited enzyme (D) Co-operative enzyme

Answer»

(B) Constitutive enzyme

250.

An inducer is absent in the type of enzyme: (A) Allosteric enzyme (B) Constitutive enzyme (C) Co-operative enzyme (D) Isoenzymic enzyme

Answer»

(B) Constitutive enzyme