Biomolecules MCQs with Answers

Question-1. A nucleotide is formed of

1. Purine, pyrimidine and phosphate
2. Nitrogen base, sugar and phosphate
3. Pyrimidine, sugar and phosphate
4. Purine, sugar and phosphate

Question-2. A polysaccharide, which is synthesized and stored in liver cells, is

1. glycogen
2. lactose
3. galactose
4. arabinose

Question-3. A segment of DNA has 120 adenine and 120 cytosine bases. The total number of nucleotides present in the segment is

1. 480
2. 120
3. 240
4. 60

Question-4. Adenine is

1. nucleotide
2. purine
3. pyrimidine
4. nucleoside

Question-5. An enzyme brings about

1. reduction in activation energy
2. decrease in reaction time
3. increase in reaction time
4. increase in activation energy

Question-6. ATP is a

1. purine
2. nucleotide
3. nucleosome
4. nucleoside

Question-7. Bonds that do not exist in tertiary structure of proteins

1. Covalent bonds
2. Phosphodiester bonds
3. Hydrophobic etnractions
4. Ionic bonds

Question-8. Cellulose, the most important constituent of plant cell wall is made of

1. branched chain of glucose molecules linked by a 1, 6 glycosidic bond at the site of branching
2. unbranched chain of glucose molecules linked by a 1, 4 glycosidic bond
3. branched chain of glucose molecules linked by ß 1, 4 glycosidic bond in straight chain and a 1,6 glycosidic bond at the site of branching
4. unbranched chain of glucose molecules linked by ß 1, 4 glycosidic bond

Question-9. Cleavage of specific covalent bonds and removal of groups without hydrolysis is the property of

1. Hydrolases
2. Lyases
3. Transferases
4. Isomerases

Question-10. Cofactor (coenzyme) is a part of holoenzyme it is

1. None of the above
2. loosely attached inorganic part
3. accessory non-protein substance attached firmly
4. loosely attached organic part

Question-11. Conjugated proteins containing carbohydrates as prosthetic group are known as

1. nucleoproteins
2. chromoproteins
3. glycoproteins
4. lipoproteins

Question-12. Cytochrome is

1. lipid
2. metallo flavoprotein
3. Fe containing porphyrin pigment
4. glycoprotein

Question-13. DNA is composed of repeating units of

1. deoxyribonucleotides
2. ribonucleosides
3. deoxyribonucleosides
4. ribonucleotides

Question-14. DNA synthesis can be specifically measured by estimating the incorporation of radio labelled

1. deoxyribose sugar
2. uracil
3. adenine
4. thymidine

Question-15. Due to discovery of which of the following in 1980 the evolution was termed as RNA world?

1. RNA is not found in all cells
2. mRNA, tRNA, rRNA synthesize proteins
3. In some virus RNA is genetic material
4. RNA have enzymatic property

Question-16. Enzyme first used for nitrogen fixation is

1. transaminase
2. nitrogenase
3. nitroreductase
4. transferase

Question-17. Enzymes are absent in

1. viruses
2. algae
3. fungi
4. cyanobacteria

Question-18. Enzymes enhance the rate of reaction by

1. lowering the activation energy of the reaction
2. forming a reactant-product complex
3. changing the equilibrium point of the reaction
4. combining with the product as soon as it is formed

Question-19. Enzymes having slightly different molecular structure but performing identical activity are

1. coenzymes
2. homoenzymes
3. isoenzymes
4. apoenzymes

Question-20. Enzymes that catalyse removal of groups from substrates by mechanisms other than hydrolysis, and addition of groups to double bonds, are called

1. None of these
2. lyases
3. dehydrogenases
4. Both

Question-21. Essential amino acids include

1. tryptophan
2. all of these
3. valine
4. leucine

Question-22. Feedback inhibition of an enzymatic reaction is caused by

1. rise in temperature
2. end product
3. substrate
4. enzyme

Question-23. Genes are packaged into a bacterial chromosome by

1. actin
2. histones
3. basic proteins
4. acidic proteins

Question-24. Glycogen is a polymer of

1. fructose
2. glucose
3. sucrose
4. galactose

Question-25. In plants, inulin and pectin are

1. insect-attracting material
2. reserve materials
3. wastes
4. excretory material

Question-26. In RNA, thymine is replaced by

1. None of these
2. Uracil
3. Guanine
4. Both

Question-27. In which one of the following groups, all the three are examples of polysaccharides?

1. Galactose, starch, sucrose
2. Starch, glycogen, cellulose
3. Sucrose, maltose, glucose
4. Glucose, fructose, lactose

Question-28. Lactose is composed of

1. glucose + galactose
2. glucose + glucose
3. glucose + fructose
4. fructose + galactose

Question-29. Length of one turn of the helix in a B-form DNA is approximately

1. None of these
2. 3.4 nm
3. 0.34 nm
4. Both

Question-30. Living cell contains 60-75% water. Water present in human body is

1. 65-70%
2. 60-65%
3. 50-55%
4. 75-80%

Question-31. Most abundant organic compound on earth is

1. Lipids
2. Cellulose
3. Steroids
4. Protein

Question-32. Most diverse macromolecules, found in the cell both physically and chemically are

1. lipids
2. proteins
3. carbohydrates
4. nucleic acids

Question-33. One of the similarities between DNA and RNA is that both

1. have similar pyrimidine bases
2. are polymers of nucleotides
3. are capable of replicating
4. have similar sugars

Question-34. Protein synthesis in a cell takes place

1. only in the cytoplasm
2. in cytoplasm as well as in mitochondria
3. in the nucleolus as well as in cytoplasm
4. only on ribosomes attached to the nuclear envelope

Question-35. Radioactive thymidine when added to the medium surrounding living mammalian cells gets incorporated into the newly synthesized DNA. Which of the following types of chromatin is expected to become radioactive if cells are exposed radioactive thymidine as soon as they enter the S-phase?

1. Neither heterochromatin nor euchromatin but only the nucleolus
2. Heterochromatin
3. Euchromatin
4. Both a) and b)

Question-36. Spoilage of oil can be detected by which fatty acid?

1. Erucic acid
2. Oleic acid
3. Linolenic acid
4. Linoleic acid

Question-37. The basic unit of nucleic acid is

1. nucleotide.
2. pentose sugar
3. nucleoid
4. nucleoside

Question-38. The enormous diversity of protein molecules is due mainly to the diversity of

1. amino groups on the amino acids
2. amino acid sequences within the protein molecule
3. peptide bonds
4. R groups on the amino acids

Question-39. The enzymes hexokinase which catalyses glucose to glucose-6-phosphate in glycolysis is inhibited by glucose- 6-phosphate. This is an example of

1. None of these
2. feedback allosteric inhibition
3. non-competitive inhibition
4. competitive inhibition

Question-40. The four elements making 99% of living system are

1. CNOP
2. CHOS
3. CHOP
4. CHON

Question-41. The helical structure of protein is stabilized by

1. None of these
2. Hydrogen bonds
3. Disulphide bonds
4. Peptide bonds

Question-42. The most basic amino acid is

1. Glutamine
2. Arginine
3. Glycine
4. Histidine

Question-43. The nitrogenous organic base purine occurring in RNA is

1. uracil
2. cytosine
3. thymine
4. guanine

Question-44. The pyrenoids are made up of

1. core of nucleic acid surrounded by protein sheath
2. proteinaceous centre and starchy sheath
3. core of protein surrounded by fatty sheath
4. core of starch surrounded by sheath of protein

Question-45. The RNA that picks up specific amino acids from the amino acid pool in the cytoplasm to ribosome during protein synthesis is called

1. carrier RNA
2. mRNA
3. tRNA
4. rRNA

Question-46. The transfer RNA molecule in 3D appears

1. S-shaped
2. L-shaped
3. E-shaped
4. Y-shaped

Question-47. Two free ribonucleotide units are interlinked with

1. phosphodiester bond
2. peptidebond
3. covalent bond
4. hydrogen bond

Question-48. Types of RNA polymerase required in nucleus for RNA synthesis

1. 4
2. 1
3. 2
4. 3

Question-49. What is common among amylase, rennin and trypsin?

1. These act at a pH lower than 7
2. These are all proteins
3. These are proteolytic enzymes
4. These are produced in stomach

Question-50. Which group contains biocatalysts?

1. Myosin, oxytocin, adrenalin
2. Peptidase, amylase, rennin
3. Glucose, amino acids, fatty acids
4. Rhodopsin, pepsin, steapsin

Question-51. Which is an essential amino acid?

1. Phenylalanine
2. Serine
3. Aspartic acid
4. Glycine

Question-52. Which is distributed more widely in a cell?

1. Spherosomes
2. DNA
3. RNA
4. Chloroplasts

Question-53. Which is wrong about nucleic acids?

1. One turn of Z-DNA has 12 bases
2. DNA is single stranded in some viruses
3. RNA is double stranded occasionally
4. Length of one helix is 45 Å in B-DNA

Question-54. Which of the following is not a part of enzyme but it activates the enzyme?

1. Si
2. K
3. C
4. N

Question-55. Which of the following sets contains polysaccharides?

1. Glucose, fructose, lactose
2. Starch, glycogen, cellulose
3. Sucrose, maltose, cellulose
4. Galactose, starch, sucrose

Question-56. Which one of the following statements about cytochrome 450 is wrong?

1. It is an enzyme involved in oxidation reactions
2. It contains iron
3. It is a coloured cell
4. It has an important role in metabolism

Question-57. An enzyme brings about

1. decrease in reaction time
2. reduction in activation energy
3. increase in activation energy
4. increase in reaction time

Question-58. Carrier ions like Na+ facilitate the absorption of substances like:

1. fructose and some amino acids
2. amino acids and glucose
3. glucose and fatty acids
4. fatty acids and glycerol

Question-59. Oils are rich in

1. Saturated fatty acids
2. Fats that are generally liquid at room temperature
3. Glycerol that possesses three hydroxyl groups
4. Esters of fatty acids