PMT Foundation – Biomolecules Practice questions

Which is not a protein?
(a) a-amylase (b) Nitrogenase
(c) Histidine kinase (d) Ribozyme
2. Arachidonic acid gives rise to
(a) terpenes (b) prostaglandins
(c) gangliosides (d) cerebrosides.
3. Which of the following nucleotide sequences contains 4 pyrimidine bases?
(a) GATCAATGC (b) GCUAGACAA
(c) UAGCGGUAA (d) Both (b) and (c).
4. Which one of the following statements regarding enzyme inhibition is correct?
(a) Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein.
(b) Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme.
(c) Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate.
(d) Non-competitive inhibitors often bind to the enzyme reversibly.
5. The given figure shows three velocity-substrate concentration curves for an enzyme reaction. What do the curves x, y, and z depict respectively ?

https://www.hourlybook.com/wp-content/uploads/2015/02/velocity-substrate-concentration-hourlybook-com.png

(a) x-normal enzyme reaction, y-competitive inhibition, z-non-competitive inhibition
(b) x-enzyme with an allosteric modulator added, y-normal enzyme activity, z-competitive inhibition
(c) x-enzyme with an allosteric stimulator, y-competitive inhibition added z-normal enzyme reaction
(d) x-normal enzyme reaction, y-non-competitive inhibitor added z-allosteric inhibitor added

6. If corn is immersed in the boiling water and then cooled, then the solution becomes sweet as
(a) monosaccharides are converted to disaccharides
(b) enzymes are inactivated in boiling water
(c) disaccharides are converted to monosaccharides
(d) none of the above.
7. The organic compound having polyhydroxy aldehydes or ketones is
(a) carbohydrate (b) lipid
(c) protein (d) vitamin.
8. Non-essential amino acids combination is
(a) valine, leucine, glycine, alanine
(b) glycine, serine, proline, glutamic acid
(c) proline, aspartic acid, glutamic acid, methionine
(d) cysteine, tyrosine, alanine, isoleucine.
9. Which of the following minerals are needed for the activity of enzymes required for the synthesis of oligosaccharides and glycoproteins?
(a) Mn (b) Mg
(c) Cu (d) Mo
10 . Which of the following is incorrect ?
(a) The hair protein, keratin, is synthesized from the amino acid methionine.
(b) Heparin is a mucopolysaccharide and an anticoagulant.
(c) Dietary intake of PUFA is recommended for persons with high blood chloesterol.
(d) Cobalt is a constituent of vit. B12.
11 . Match the biological molecule listed under column-l with their biological functions listed under column – II; choose the answer which gives correct combination of alphabets of the two columns.

Column I
(Biological molecules)
Column II
(Functions)
A. Glycogen p.  Hormone
B. Globulin q.  Biocatalyst
C. Steroids r.  Antibody
D. Thrombin s.  Storage product

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12. High lysine content is present in
(a) bajra (b) wheat
(c) maize (d) rice.

13 . Which statement regarding coenzyme is incorrect?
(a) Every coenzyme is a cofactor and every cofactor is a coenzyme.
(b) Every coenzyme is a cofactor but every cofactor is not a coenzyme.
(c) Most of the coenzymes are nucleotides and are composed of vitamins.
(d) Coenzymes are the active constituents of enzymes.
l4. Arrange the steps of catalytic action of an enzyme in order and choose the correct option.
I. The enzyme releases the products of the reaction and gets free for another substrate.
II. The active site of enzyme is in close proximity of the substrate and breaks of chemical bonds of the substrate.
III. The binding of substrate induces the enzyme to alter its shape, fitting more tightly around the substrate.
IV. The substrate binds to the active sites of the enzyme, fitting into the active sites.
(a) IV, III, II and I (b) III, II, I and IV
(c) IV, II, I and III (d) II, I, IV and III

15 . Match the following columns

Column -1 Column -2
A. Triglyceride (i) Animal hormones
B. Membrane lipid (ii) Feathers and leaves
C. Steroid (iii) Phospholipids
D. Wax (iv) Fat stored in the form of
lipids.

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True or False Questions

16. Metabolic reactions in the cells of our body are both catalysed as well as uncatalysed reactions.
17. The living state is an equilibrium steady state capable of performing work.
18. An active site of an enzyme is a convexity on its surface, that fits into the concavity on the surface of the substrate.
19. Secondary metabolites of plant, fungal and microbial cells do not have a major role in their physiological processes, but are useful for human welfare.
20. Essential amino acids are those which are much needed by our body and so are synthesized by our body.
21. Quaternary structure is absolutely necessary for the many biological activities of enzymes.
22. Three kinds of coenzymes are identified-prosthetic groups, co-factors and metal ions.
23. Proteins are made up of repeating units of amino acids, linked together by peptide bond, and are so called homopolymers.
24. All enzymes are proteins e.g., pepsin, ribozyme and have a primary, secondary, tertiary and quaternary structure.
25. The formation of E + S complex is essential for catalysis.

Match The Columns type questions

26. Match Column-I with Column-ll.

Column-I Column-II
A. Nucleoside (i) Lecithin
B. Glucose transport (ii) Thymidylic acid
C. Secondary metabolite (iii) GLUT 4
D. Primary metabolite (iv) Vinblastin
E. Fatty acid (v) Arachidonic acid
F. Phospholipid (vi) Cytidine
G. Nucleotide (vii) Antibiotics

27. Match Column-I with Column-ll. There can be more than one correct matches for items in Column-I

Column I Column II
A. Neutral amino acid (i) Lysine
B. Fibrous protein (ii) Keratin
C. Coenzymes (iii) FMN
D. Lyases (iv) Histone
E. Globular protein (v) Glycosidase
F. Hydrolases (vi) Glutelin
G. Basic amino acid (vii) Aldolase
(viii) Esterase
(ix) Glycine
(x) Carboxylase
(xi) CoA
(xii) Collagen
(xiii) Leucine
(xiv) Arginine

Passage Based Questions

28.(A) Complete the given passage with appropriate words or phrases.
For nucleic acids, the building block is a (i) which consists of (ii) chemically distinct components, one is a (iii) compound, the second is a (iv) and the third is (v) acid.

(B) Read the passage and correct the errors, wherever present.
Proteins are homopolymers containing strings of amino acids. A protein is imagined as a line, the right end represented by the first amino acid, and the left end represented by the last amino acid. The first amino acid is also called as (C) terminal amino acid, while the last amino acid is called the (N) terminal amino acid.

Assertion & Reason

In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, mark the correct answer as:
(a) if both A and R are true and R is the correct explanation of A
(b) if both A and R are true but R is not the correct explanation of A
(c) if A is true but R is false
(d) if both A and R are false.
29. Assertion : Starch gives blue colour with iodine, but not cellulose.
Reason : Starch forms helical secondary structures which can hold iodine, but cellulose does not contain helices, and so cannot hold iodine.
30. Assertion: Oxygen is most abundant element in the human body and in the earth’s crust.
Reason : It is about 65% in the earth’s crust and 46.6% in the human body.
31. Assertion : The lipids, with a molecular weight of 800 Da are micromolecules.
Reason : They are obtained in the acid soluble micromolecular fraction.
32. Assertion : The structure of amino acids changes in solutions of different pHs.
Reason : This is due to the ionisable nature of -NH2 and -COOH groups.
33. Assertion : Purines are smaller sized nitrogenous bases which are 6 membered.
Reason : Pyrimidines are larger sized nitrogenous basis which are 9 membered.
34. Assertion : Km indicates affinity of the enzyme for its substrate.
Reason : A high Km indicates high affinity while low Km indicates low affinity.

35. Assertion : Both competitive and allosteric inhibition have a regulatory function.
Reason : They stop the excess formation of a product.
36. Assertion : Collagen is the most abundant protein of the complete biosphere.
Reason : Rubisco is the most abundant protein of plants.
37. Assertion: Most monosaccharides have asymmetrical carbon atoms.
Reason : They are able to rotate polarised light to the right or left side.
38. Assertion : Enzymes are highly specific in their action.
Reason : Different enzymes may act on the same substrate, but give rise to different products.

Figure Based Questions

39. Refer to the graph below and identify the labelled parts – A,B,C,D,E and given number 1 and 2.

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40. Refer to the given figure again and fill in the blanks using the appropriate alphabets of the labelled parts- A, B, C, D, E and the given numbers.
(i) If_____is at a lower energy level than______ the reaction is exothermic.
(ii) When_____binds to the enzyme active site, _____is formed, (enzyme substrate complex)
(iii) ln the graph___represents activation energy without enzyme while_____represents activation energy with enzyme.

Answers

I. (d) 2. (b) 3. (a) 4. (b) 5. (a)
6. (c) 7. (a) 8. (b) 9. (a) 10. (a)
II. (d) 12. (a) 13. (a) 14. (a) 15. (a)
16. False. They are all catalysed reactions, and there are no uncatalysed metabolic conversions in living systems.
17. False. The living state is a non-equilibrium steady state, performing work.
18. False. The active site of an enzyme is a crevice or pocket into which the substrate fits.
19 True
20. False. Essential amino acids are obtained through the diet, while non-essential are synthesized by our body.
21. False. Tertiary structure is absolutely necessary for the many biological activities of enzymes.
22. False. Three kinds of cofactors are identified- prosthetic groups, co-enzymes and metal ions.
23. False. Proteins are heteropolymers containing different amino acids.
24. False. Ribozyme is nucleic acid.
25. False. The formation of ES complex is essential for catalysis.
26. A-(vi), B-(iii), C-(iv), D-(vii), E-(v), F-(i), G-(ii)
27. A-(ix, xiii), B-(ii, xii), C-(iii, xi), D-(vii, x), E-(iv, vi), F-(v, viii), G-(i, xiv)
28. (A) (i) Nucleotide, (ii) three, (iii) heterocyclic, (iv)
monosaccharide, (v) phosphoric.
(B) Proteinsare homopolymers heteropolymerscontaining strings of amino acids. A protein is imagined as a line, the fight left end represented by the first amino acid, and the left right end represented by the last amino acid. The first amino acid is also called as € N terminal amino acid, while the last amino acid is called the N C terminal amino acid.
29. (a) 30. (c) 31. (c) 32. (a) 33. (d)
34. (c) 35. (d) 36. (d) 37. (b) 38. (b)
39. A – Product, B – Progress of reaction
C-Transition state, D-Potential energy E-Substrate, 1 – Activation energy (Enzymatic reaction), 2- Activation energy (Non-enzymatic reaction).
40. (i) A, E; (ii) E, C; (iii) 2, 1.

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