Biology MCQs with Answer by General knowledge Solutions

Biology MCQs with Answer  by General knowledge Solutions

                                                                                     

01. Chain elongation of fatty acids in mammalian liver occurs in

(A) Nucleus

(B) Ribosomes

(C) Lysosomes

(D) Microsomes

02. Acetyl-CoA is the principal building block of fatty acids. It is produced within the mitochondria and does not diffuse readily into cytosol. The availability of acetyl CoA involves

(A) Carnitine acyl transferase

(B) Pyruvate dehydrogenase

(C) Citrate lyase

(D) Thiolase

03. The synthesis of fatty acids is often termed reductive synthesis.

(A) NADP+

(B) NADH

(C) FADH2

(D) NADPH

04. 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

05. The fatty acid synthase complex catalyses

(A) 4 sequential enzymatic steps

(B) 6 sequential enzymatic steps

(C) 7 sequential enzymatic steps

(D) 8 sequential enzymatic steps

06. The main source of reducing equivalents (NADPH) for lipogenesis is

(A) Pentose phosphate pathway

(B) Citric acid cycle

(C) Glycolysis

 (D) Glycogenolysis

07. In fatty acids synthase of both bacteria and mammals, ACP (acyl carrier protein) contain the vitamin:

(A) Thiamin

(B) Pyridoxine

(C) Riboflavin

(D) Pantothenic acid

08. Carboxylation of acetyl-CoA to malonylCoA requires the enzyme:

(A) Acetyl-CoA carboxylase

(B) Pyruvate carboxylase

(C) Acetyl transacylase

(D) Acyl CoA-synthetase

09. 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

10. Conversion of fatty acyl-CoA to an acylCoA derivative having 2 more carbon atoms involves as acetyl donar:

(A) Acetyl-CoA

(B) Succinyl-CoA

(C) Propionyl-CoA

(D) Malonyl-CoA

11. A cofactor required for the conversion of acetyl-CoA to malonyl-CoA in extramitochondrial fatty acid synthesis is

(A) Biotin

(B) FMN

(C) NAD

(D) NADP

12. The glycerol for fatty acid esterification in adipocytes is

(A) For the most part, derived from glucose

(B) Obtained primarily from phosphorylation of glycerol by glycerol kinase

(C) Formed from gluconeogenesis

(D) Formed from glycogenolysis

13. 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

14. The enzyme glycerol kinase is low activity in

 (A) Liver

(B) Kidney

(C) Intestine

(D) Adipose tissue

15. 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

16. Synthesis of polyunsaturated fatty acids involves the enzyme systems:

(A) Acyl transferase and hydratase

(B) Desaturase and elongase

(C) Ketoacyl-CoA reductase and hydratase

(D) Dihydroxyacetone phosphate

17. The desaturation and chain elongation system of polyunsaturated fatty acid are enhanced by

(A) Insulin

(B) Glucagon

(C) Epinephrine

(D) Thyroxine

18. Higher rate of lipogenesis is associated with

(A) High proportion of carbohydrate in diet

(B) Restricted caloric intake

(C) High fat diet

(D) Deficiency of insulin

19. Example of enzyme specificity:

(A) Stereo specificity

(B) Reaction specificity

(C) Substrate specificity

(D) All of these

20. Phospholipase C attacks the ester bond liberating 1, 2-diacylglycerol and a phosphoryl base at position

(A) 1

(B) 2

(C) Both (A) and (B)

(D) 3

21. Synthesis of phosphatidylinositol by transfer of inositol to CDP diacylglycerol is catalysed by the enzyme:

(A) CTP phosphatidate cytidyl transferase

 (B) Phosphatidate phosphohydrolase

(C) CDP-diacylglycerol inositol transferase

(D) Choline kinase

22. Synthesis of sphingosine requires the cofactor

(A) NAD

(B) NADP

(C) NADPH+

(D) ATP

23. Ceramide is formed by the combination of sphingosine and

(A) Acetyl-CoA

(B) Acyl-CoA

(C) Malonyl-CoA

(D) Propionyl-CoA

24. The amino alcohol sphingosine is synthesized in

(A) Mitochondria

(B) Cytosol

(C) Nucleus

(D) Endoplasmic reticulum

25. The output of free fatty acids from adipose tissue is reduced by

(A) Insulin

(B) Glucagon

(C) Growth hormone

(D) Epinephrine

26. The principal action of insulin in adipose tissue is to inhibit the activity of the

(A) Hormone sensitive lipoprotein lipase

(B) Glycerol phosphate acyltransferase

(C) Acetyl-CoA carboxylase

(D) Pyruvate dehydrogenase

27. In non shivering thermogenesis

(A) Glucose is oxidized to lactate

(B) Fatty acids uncouple oxidative phosphorylation

(C) Ethanol is formed

(D) ATP is burned for heat production

28. Brown adipose tissue is

(A) A prominent tissue in human

(B) Characterised by high content of mitochondria

(C) Associated with high activity of ATP synthase

(D) Characterised by low content of cytochromes

29. Fatty liver is caused due to accumulation of

(A) Fatty acids

(B) Cholesterol

(C) Phospholipids

(D) Triacylglycerol

30. A lipotropic factor is

(A) Choline

(B) Palmitic acid

(C) Calcium

(D) Vitamin C

31. Fatty liver is also caused by

(A) CH3Cl

(B) CCl4

(C) Na2SO4

(D) Riboflavin

32. All the enzymes involved in the synthesis of cholesterol are found in

(A) Mitochondria

(B) Golgi apparatus

(C) Nucleus

(D) Endoplasmic reticulum and cytosol

33. The source of all the carbon atoms in cholesterol is

 (A) Acetyl-CoA

(B) Bicarbonate

(C) Propionyl-CoA

(D) Succinyl-CoA

34. Two molecules of acetyl-CoA condense to form acetoacetyl-CoA catalysed by

(A) Thiolase

(B) Kinase

(C) Reductase

(D) Isomerase

35. Acetoacetyl-CoA condenses with one more molecule of acetyl-CoA to form

(A) Mevalonate

(B) Acetoacetate

(C) β-Hydroxybutyrate

(D) 3-Hydroxy 3-methyl-glutaryl-CoA

36. HMG-CoA is converted to mevalonate by reduction catalysed by

 (A) HMG-CoA synthetase

(B) HMG-CoA reductase

(C) Mevalonate kinase

(D) Thiolase

37. For reduction enzyme HMG-CoA reductase requires cofactor:

(A) NADPH

(B) NADP

(C) NAD

(D) FAD

38. In the biosynthesis of cholesterol, the step which controls the rate and locus of metabolic regulation is

(A) Geranyl pyrophosphate farnesyl pyrophosphate

(B) Squalene → lanosterol

(C) HMG CoA → mevalonate

 (D) Lanosterol → 1, 4-desmethyl lanosterol

39. The cyclisation of squalene in mammals results in the direct formation of the sterol.

(A) Cholesterol

(B) Lanosterol

(C) Sistosterol

(D) Zymosterol

 40. In the biosynthesis of cholesterol, the rate limiting enzyme is

(A) Mevalonate kinase

(B) HMG-CoA synthetase

(C) HMG-CoA reductase

(D) Cis-prenyl transferase

 41. Cholesterol by a feed back mechanism inhibits the activity of

(A) HMG-CoA synthetase

(B) HMG-CoA reductase

(C) Thilase

(D) Mevalonate kinase

Answers

01. D 02. C 03. D 04. D 05. B 06. A 07. D 08. A 09. A 10. D 11. A 12. A 13. D 14. D 15. A 16. A 17. A 18. A 19. D 20. D 21. C 22. C 23. B 24. D 25. A 26. A 27. B 28. B 29. D 30. A 31. B 32. D 33. A 34. A 35. D 36. B 37. A 38. C 39. B 40. C 41. B