70 MULTIPLE CHOICE QUESTIONS
Attempt all questions. Read each question carefully and select the BEST option. Some questions have 4 options, others 5 options. You have 2 HOURS. 1. The most active site of protein synthesis is the:
a. b. c. d.
Nucleus Ribosome Mitochondrion Cell sap
2. The Golgi complex:
a. b. c. d.
Synthesizes proteins Produces ATP Provides a pathway for transporting chemicals Forms glyco-proteins
3. The general formula of monosaccharides is:
a. b. c. d.
CnH2nOn C2nH2On CnH2O2n CnH2nO2n
4. A triose sugar is:
a. b. c. d.
Glycerose Ribose Erythrose Fructose
5. A pentose sugar is:
a. b. c. d.
Dihydroxyacetone Ribulose Erythrose Glucose
6. The number of isomers of glucose is:
a. b. c. d.
2 4 8 16
7. Two sugars which differ from one another only in configuration around a single carbon
atom are termed: a. b. c. d.
Epimers Anomers Optical Isomers Stereoisomers
8. The most important epimer of glucose is:
a. b. c. d.
Galactose Fructose Arabinose Xylose
9. The sugar found in RNA is:
a. b. c. d.
Ribose Deoxyribose Ribulose Erythrose
10. The sugar found in milk is:
a. b. c. d.
Galactose Glucose Fructose Lactose
11. Sucrose consists of:
a. b. c. d.
Glucose + glucose Glucose + fructose Glucose + galactose Glucose + mannose
12. Starch is a:
a. b. c. d.
Polysaccharide Monosaccharide Disaccharide None of these
13. The most abundant carbohydrate found in nature is:
a. b. c. d.
Starch Glycogen Cellulose Chitin
14. Branching occurs in glycogen approximately after every
a. b. c. d.
Five glucose units Ten glucose units Fifteen glucose units Twenty glucose units
15. The optically inactive amino acid is:
a. b. c. d.
Glycine Serine Threonine Valine
16. At neutral pH, a mixture of amino acids in solution would be predominantly:
a. b. c. d.
Dipolar ions Nonpolar molecules Positive and monovalent Hydrophobic
17. An example of polar amino acid is:
a. b. c. d.
Alanine Leucine Arginine Valine
18. An amino acid not found in proteins is:
a. b. c. d.
β-Alanine Proline Lysine Histidine
19. In proteins the α-helix and β-pleated sheet are examples of:
a. b. c. d.
Primary structure Secondary structure Tertiary structure Quaternary structure
20. At the lowest energy level α-helix of polypeptide chain is stabilized:
a. b. c. d.
By hydrogen bonds formed between the H of peptide N and the carbonyl O of the residue Disulphide bonds Non polar bonds Ester bonds
21. Denaturation of proteins results in:
a. b. c. d.
Disruption of primary structure Breakdown of peptide bonds Destruction of hydrogen bonds Irreversible changes in the molecule
22. At a pH below the isoelectric point, an amino acid exists as:
a. b. c. d.
Cation Anion Zwitterion Undissociated molecule
23. Primary structure of a protein is formed by:
a. b. c. d.
Hydrogen bonds Peptide bonds Disulphide bonds All of these
24. Which of the following statement about the peptide bond is true?
a. b. c. d.
It is a carbon-carbon bond It has cis hydrogen and oxygen groups It is planar It has rotational freedom
25. Optically active compounds are capable of:
a. b. c. d.
Different reactions Rotating plane of polarized light Showing same chemical properties None of these
26. Side chains of all amino acids contain aromatic rings except:
a. b. c. d.
Phenylalanine Alanine Tyrosine Tryptophan
27. Isoelectric pH of an amino acid is that pH at which it has a:
a. b. c. d.
Positive charge Negative charge No charge None of these
28. In mammals, the major fat in adipose tissues is:
a. b. c. d.
Phospholipid Cholesterol Sphingolipids Triacylglycerol
29. The importance of phospholipids as constituent of cell membrane is because they
possess: a. b. c. d.
Fatty acids Both polar and non-polar groups Glycerol Phosphoric acid
30. Triglycerides are:
a. b. c. d.
Heavier than water Major constituents of membranes Non-polar Hydrophilic
31. The major storage form of lipids is:
a. b. c. d.
Esterified cholesterol Glycerophospholipids Triglycerides Sphingolipids
32. All the following have 18 carbon atoms except:
a. b. c. d.
Linoleic acid Linolenic acid Arachidonic acid Stearic acid
33. A nucleoside consists of:
a. b. c. d.
Nitrogenous base Purine or pyrimidine base + sugar Purine or pyrimidine base + phosphorous Purine + pyrimidine base + sugar + phosphorous
34. The chemical name of guanine is:
a. b. c. d.
2,4-Dioxy-5-methylpyrimidine 2-Amino-6-oxypurine 2-Oxy-4-aminopyrimidine 2, 4-Dioxypyrimidine
35. The carbon of the pentose in ester linkage with the phosphate in a nucleotide structure is:
a. b. c. d.
C1 C3 C4 C5
36. The most abundant free nucleotide in mammalian cells is:
a. b. c. d.
ATP NAD GTP FAD
37. In RNA molecule guanine content does not necessarily equal its cytosine content nor
does its adenine content necessarily equal its uracil content since it is a: a. b. c. d.
Single strand molecule Double stranded molecule Double stranded helical molecule Polymer of purine and pyrimidine ribonucleotides
38. Double helical structure model of the DNA was proposed by:
a. b. c. d.
Pauling and Corey Peter Mitchell Watson and Crick King and Wooten
39. DNA rich in A-T pairs have:
a. b. c. d.
1 Hydrogen bond 2 Hydrogen bonds 3 Hydrogen bonds 4 Hydrogen bonds
40. The fact that DNA bears the genetic information of an organism implies that:
a. b. c. d.
Base composition should be identical from species to species DNA base composition should charge with age DNA from different tissues in the same organism should usually have the same base composition DNA base composition is altered with nutritional state of an organism
41. In a DNA molecule the thymine concentration is 30%, the guanosine concentration will be:
a. b. c. d.
10% 20% 30% 40%
42. Genetic information flows from:
a. b. c. d.
DNA to DNA to RNA to DNA to
DNA RNA cellular proteins cellular proteins
43. Genetic code is:
a. b. c. d.
Collection of codon Collection of amino acids Collection of purine nucleotides Collection of pyrimidine nucleotides
44. Degeneracy of genetic code implies that:
a. b. c. d.
Codons do not code for specific amino acid Multiple codons must decode the same amino acids No anticodon on tRNA molecule Specific codon decodes many amino acids
45. mRNA is complementary to the nucleotide sequence of:
a. b. c. d.
Coding strand rRNA tRNA Template strand
46. In nucleotides, phosphate is attached to sugar by:
a. b. c. d.
Salt bond Hydrogen bond Ester bond Glycosidic bond
47. Mitochondrial DNA is present in:
a. b. c. d.
Bacteria Viruses Eukaryotes All of the above
48.Transfer RNA transfers:
a. b. c. d.
Information from DNA to ribosome’s Information from mRNA to cytosol Amino acids from cytosol to ribosomes Proteins from ribosomes to cytosol
49. Which of the following compounds are bonded to phosphate in diacyl phosphoglycerol to
complete the repertoire of phospholipids found in body membranes? a. b. c. d. e.
Only choline Betaine and sphingosine Choline, betaine, and sphingosine Choline, serine, and sphingosine Choline, serine, ethanolamine, inositol
50. Proline disrupts-helical structure in proteins because it is
a. b. c. d. e.
An acidic amino acid An aromatic amino acid An imino acid A basic amino acid A sulfur-containing amino acid
51. Water is generally a good solvent for polar molecules and a poor solvent for nonpolar
molecules. These solvent properties are best explained by a. b. c. d. e.
The high density of liquid water relative to polar solvents The ability to form intermolecular hydrogen bonds The density of solid water being less than the density of liquid water High surface tension High heat of vaporization
52. Which of the following pairs of molecules could NOT hydrogen bond with each other?
53. All of the following are sulphur containing amino acids found in proteins EXCEPT:
a. b. c. d.
Cysteine Cystine Methionine Threonine
54. Which of the following functional groups behaves as a weak acid, i.e., dissociate a proton
in aqueous solution, at physiological pH? a. b. c. d. e.
R—CH2—R' RCH2—OH R—NH3+ R—COOH Ph—OH
55. The C1 of ribose and glucose has all of the following properties EXCEPT ONE. Which is
the EXCEPTION? a. Anomeric carbon forms α/β racemic mixture. b. Acyl aldehyde groups react with primary and secondary alcohols and amines. c. D/L isomers define the specific optical rotation. d. In solution, mutarotation of either pure intramolecular hemiacetal yields an equilibrium mixture of α/β anomers. e. Forms acetal ribosides and glucosides, respectively, that can’t mutarotate. 56. All of the following are characteristic of amino acids EXCEPT.
a. b. c. d. e.
The α-carbon (C2) is a chiral center (except for glycine). All migrate to the cathode in an electric field at physiological pH. They have side chains with different physical and chemical properties. Most can form dipolar ions (zwitterions) at physiological pH. Only a repertoire of 20 amino acids are incorporated into proteins.
57. Select the INCORRECT statement about lipids.
a. b. c. d. e.
Lipids are small nonpolar molecules extracted by organic solvents. Most of our fat is stored as triglyceride droplets in adipose tissue cells. Phospholipids are the major class of lipids in membranes. ABO-blood group antigens are glycosphingolipids (glycolipids). Most fatty acids are present as free acids in cells.
58. Select the statement about glycogen biochemistry that is INCORRECT.
a. b. c. d. e.
Glycogen is composed of highly branched chains of α−glucose residues. Glycogen’s outward branching provides reactive ends for extremely rapid incorporation and release of glucose. Glucose residues are linked by acetal α(1 → 4) bonds. Appr oximately 1 in 8 glucose residues are linked by an acetal α(1 → 6) bond. Glycogen is hydrophilic and therefore is less dense than triacylglycerides.
59. The partial negative charge on oxygen and partial positive charge on hydrogen makes
water a polar sovent and enables what? a. b. c. d.
Hydrogen bonds Covalent bonds Ionic bonds Van der waals interactions
60. What best describe amylopectin?
a. b. c. d.
Unbranched linear polymer with alpha 1-4 glycosidic linkages Unbranched linear polymer with beta 1-4 glycosidic linkages Highly branched, branched sites contain alpha 1-6 glycosidic linkages Highly branched, branched sites contain beta 1-6 glycosidic linkages
61. Which of this is NOT a typical role for lipid in living organism?
a. b. c. d. e.
Provide stored energy reserved Form a structural component of cell membrane and many tissues A source of glucose when broken down A material from which the hormone can be produced Protection of internal organs, insulation beneath skin
62. A nucleotide consists of
a. b. c. d.
A nitrogenous base like choline Purine + pyrimidine base + sugar + phosphorous Purine or pyrimidine base + sugar Purine or pyrimidine base + phosphorous
63. A pyrimidine nucleotide is
a. b. c. d.
GMP AMP CMP IMP
64. The nucleic acid base found in mRNA but not in DNA is
a. b. c. d.
Adenine Cytosine Guanine Uracil
65. In every cell, the number of tRNA molecules is at least
a. b. c. d.
10 20 30 40
66. In DNA molecule
a. b. c. d.
Guanine content does not equal cytosine content Adenine content does not equal thymine content Adenine content equals uracil content Guanine content equals cytosine content
67. Genetic code is
a. b. c. d.
Overlapping Non-overlapping Not universal Ambiguous
68. The first codon to be translated on mRNA is
a. b. c. d.
AUG GGU GGA AAA
69. In biosynthesis of proteins the chain terminating codons are
a. b. c. d.
UAA, UAG and UGA UGG, UGU and AGU AAU, AAG and GAU GCG, GCA and GCU
70. Reverse transcriptase is capable of synthesizing
a. b. c. d.
RNA → DNA DNA → RNA RNA → RNA DNA → DNA
