Medical Exam-Biology  Biomolecules  Practice Q & A

1. The curve given below show enzymatic activity with relation to three conditions (pH, temperature and

substrate concentration). What do both axes (x and y) represent?

enzymatic-activity-curve.gif" alt="enzymatic activity curve" style="margin:0 auto;" />

x-axis y-axis

(1) enzymatic activity Temperature

(2) enzymatic activity pH

(3) Temperature enzyme Activity

(4) substrate concentration enzymatic Activity

a. Option (1)

b. Option (2)

c. Option (3)

d. Option (4)

2. One strand of DNA has the following sequence of nucleotide 3 ATTCGCTAT 5 so the other strand of

DNA has

a. 5 TAAGCGATA 3

b. 3 TAAGCGATA 5

c. 5 GACGCGATA 3

d. 3 GACGCGATA 5.

3. Feedback inhibition of enzymes is affected by which of the following

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a. enzyme

b. substrate

c. end products

d. intermediate end products

4. Example of a typical homopolysaccharide is

a. Lignin

b. Suberin

c. Inulin

d. Starch

5. Hydrolysis of starch occurs with the help of

a. Peptidase

b. Amylase

c. Sucrose

d. Lipase

6. Which of the following is not a conjugated protein?

a. Peptone

b. Phosphoprotein

c. Lipoprotein

d. Chromoprotein

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7. Chitin is a

a. Polysaccharide

b. Nitrogenous polysaccharide

c. Lipoprotein

d. Protein

8. The effectiveness of an enzyme is affected least by

a. Temperature

b. Concentration of the substrate

c. Original activation energy of the system

d. Concentration of the enzyme

9. Which is an organic compound found in most cells?

a. Glucose

b. Water

c. Sodium chloride

d. Oxygen

10. Specificity of protein in enzyme action depends upon

a. Active sites

b. Km constant

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c. Linear sequence of amino acids

d. Turn over number

11. The "Repeating Unit" of glycogen is

a. Fructose

b. Mannose

c. Glucose

d. Galactose

12. Example of a typical homopolysaccharide is

a. Inulin

b. Suberin

c. Lignin

d. Starch

13. Which one of the following structural formulae of two organic compounds is correctly identified along

with its related function?

organic-compounds.gif" alt="organic compounds" style="margin:0 auto;" />

a. A : Lecithin - a component of cell membrane

b. B : Adenine - a nucleotide that makes up nucleic acids

c. A : Triglyceride - major source of energy

d. B : Uracil - a component of DNA

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14. An enzyme that joins the ends of two strands of nucleic acid is

a. polymerase

b. ligase

c. synthetase

d. helicase

15. enzymes, vitamins and hormones can be classified into a single category of biological chemicals,

because all of these

a. Are exclusively synthesized in the body of a living organism as at present

b. enhance oxidative metabolism

c. Are conjugated proteins

d. Help in regulating metabolism

16. The figure given below shows three velocity-substrate concentration curves for an enzyme reaction.

What do the curves a, b and c depict respectively?

enzyme reaction" style="margin:0 auto;" />

a. a-normal enzyme reaction, b-competitive inhibition, c-non-competitive inhibition

b. a-enzyme with an allosteric modulator added, b-normal enzyme activity, c-competitive inhibition

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c. a-enzyme with an allosteric stimulator, b-competitive inhibitor added, c-normal enzyme reaction

d. a-normal enzyme reaction, b-non-competitive inhibitor added, c-allosteric inhibitor added

17. enzymes are polymers of

a. Hexose sugar

b. Amino acids

c. Fatty acids

d. Inorganic phosphate

18. The catalytic efficiency of two different enzymes can be compared by the

a. Molecular size of the enzyme

b. The pH optimum value

c. The Km value

d. Formation of the product

19. In which one of the following sets of three items each belong to the category mentioned against them?

a. Lysine, glycine, thiamine — Amino acids

b. Myosin, oxytocin and gastric — Hormones

c. Rennin, helicase and hyaluronidase — Enzymes

d. Optic nerve, oculomotor, vagus — Sensory nerves

20. carbohydrates, the most abundant biomolecules on earth, are produced by

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a. Fungi, algae and green plants cells

b. All bacteria, fungi and algae

c. Some bacteria, algae and green plant cells

d. Viruses, fungi and bacteria

21. enzymes exist in the cells as

a. Solution

b. Crystals

c. Solids

d. Colloids

22. The enzyme responsible for the reduction of molecular nitrogen to the level of ammonia in the

leguminous root nodule is

a. nitrogenase

b. nitrate reductase

c. nitrite reductase

d. all of the above

23. Many enzymes are secreted in inactive form to protect

a. Cell Membrane

b. Mitochondria

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c. Cell proteins

d. Cell DNA

24. Assertion: Arachidic acid is an unsaturated fatty acid.

Reason: There are one or more double bonds between carbon atoms in unsaturated fatty acids.

a. Both Assertion and Reason are true and Reason is the correct explanation of the Assertion.

b. Both Assertion and Reason are true but the Reason is not the correct explanations of Assertion.

c. Assertion is true, but Reason is false.

d. Both Assertion and Reason are false.

25. Assertion: A coenzymes or metal ions that is very tightly bound to enzyme protein is called prosthetic

group.

Reason: A complete, catalytically active enzyme together with its bound prosthetic group is called

apoenzyme.

a. Both Assertion and Reason are true and Reason is the correct explanation of the Assertion.

b. Both Assertion and Reason are true but the Reason is not the correct explanations of Assertion.

c. Assertion is true, but Reason is false.

d. Both Assertion and Reason are false.

26. Which one of the following amino-acids was not found to be synthesized in Miller s experiment?

a. Glutamic acid

b. Aspartic acid

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c. Glycine

d. Alanine

27. The coenzyme is

a. often a metal

b. always a protein

c. often a vitamin

d. always an inorganic compound

28. The "lock and key" model of enzyme action illustrates that a particular enzyme molecule

a. May be destroyed and resynthesised several times

b. Interacts with a specific type of substrate molecule

c. Reacts at identical rates under all conditions

d. Forms a permanent enzyme-substrate complex

29. Which of the following is produced with the combination of apoenzyme and coenzyme?

a. Holoenzyme

b. Enzyme substrate complex

c. Prosthetic group

d. Enzyme product complex

30. An example of competitive inhibition of an enzyme is the inhibition of

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a. succinic dehydrogenase by malonic acid

b. cytochrome oxidase by cyanide

c. hexokinase by glucose-6-phosphate

d. carbonic anhydrase by carbon dioxide

31. Which one is diaminodicarboxylic amino acid?

a. Cystine

b. Lysine

c. Cysteine

d. Aspartic Acid

32. Blocking of enzyme action by blocking its active sites is

a. allosteric inhibition

b. feedback inhibition

c. competitive inhibition

d. non-competitive inhibition

33. Which one is the most abundant protein in the animal world?

a. Collagen

b. Insulin

c. Trypsin

d. Haemoglobin

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34. enzymes, vitamins and hormones are common in

a. Enhancing oxidative metabolism

b. Being synthesised in the body of organisms

c. Being proteinaceous

d. Regulating metabolism

35. Diastase takes part in digestion of ______.

a. Protein

b. Starch

c. Amino acids

d. Fat

36. enzyme catalyzing rearrangement of atomic groupings without altering molecular weight or number of

atoms is

a. ligase

b. isomerase

c. oxidoreductase

d. hydrolase

37. The general mechanism is that an enzyme acts by

a. reducing the energy of activation

b. increasing the energy of activation

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c. decreasing the pH

d. increasing the pH

38. enzyme complex involved in alcoholic fermentation is

a. Zymase

b. Invertase

c. Lipase

d. Amylase

39. zymogen or proenzyme is a

a. Modulator

b. Vitamin

c. Enzyme precursor

d. Hormone

40. enzymes are basically made up of

a. Fats

b. Proteins

c. Nucleic acids

d. Vitamins

41. Fluidity of bio-membranes can be shown by

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a. Electron microscope

b. Tissue culture

c. Phase-contrast microscope

d. Fluorescence microscope

42. The first enzyme to be purified and crystallized was

a. Urease

b. Diastase

c. Insulin

d. Zymase

43. Catalysts are different from enzymes in

a. functional at high temperature

b. not used up in reaction

c. being proteinaceous

d. having high rate diffusion

44. The enzyme which hydrolyses starch to maltose is

a. protease

b. amylase

c. lactase

d. maltase

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45. The non protein part of an enzyme is known as

a. Holoenzyme

b. Vitamin

c. Apoenzyme

d. Prosthetic group

46. Value needed for enzyme action is ______.

a. Low Km

b. Low Ki

c. High Km

d. High Ki

47. ELISA tests are used to

a. Isolate DNA sequence

b. Purity proteins

c. Separate viral RNA

d. Identify specific proteins

48. Which one of the following is resistant to enzyme action?

a. Leaf cuticle

b. Cork

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c. Wood fibre

d. Pollen exine

49. In which of the following organisms enzymes are absent

a. Fungi

b. Viruses

c. Algae

d. Bacteria

50. enzymes functional inside the cells are called

a. endoenzymes

b. exoenzymes

c. apoenzymes

d. isoenzymes

Answer Keys

1. c 2. a 3. c 4. d 5. b

6. a 7. b 8. c 9. a 10. c

11. c 12. d 13. a 14. b 15. d

16. a 17. b 18. c 19. c 20. c

21. d 22. a 23. c 24. d 25. c

26. a 27. c 28. b 29. a 30. a

31. a 32. c 33. a 34. d 35. b

36. b 37. a 38. a 39. c 40. b

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41. d 42. a 43. b 44. b 45. d

46. b 47. d 48. d 49. b 50. a

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