Biomolecules MCQs with Answers

Question-1. A nucleotide is formed of

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

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

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

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

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

Question-4. Adenine is

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

Question-5. An enzyme brings about

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

Question-6. ATP is a

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

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

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

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

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

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

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

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

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

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

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

Question-12. Cytochrome is

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

Question-13. DNA is composed of repeating units of

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

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

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

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

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

Question-16. Enzyme first used for nitrogen fixation is

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

Question-17. Enzymes are absent in

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

Question-18. Enzymes enhance the rate of reaction by

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

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

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

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

Question-21. Essential amino acids include

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

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

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

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

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

Question-24. Glycogen is a polymer of

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

Question-25. In plants, inulin and pectin are

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

Question-26. In RNA, thymine is replaced by

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

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

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

Question-28. Lactose is composed of

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

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

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

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

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

Question-31. Most abundant organic compound on earth is

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

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

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

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

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

Question-34. Protein synthesis in a cell takes place

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

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

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

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

Question-37. The basic unit of nucleic acid is

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

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

1. amino acid sequences within the protein molecule
2. peptide bonds
3. R groups on the amino acids
4. amino 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. feedback allosteric inhibition
2. non-competitive inhibition
3. competitive inhibition
4. None of these

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

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

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

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

Question-42. The most basic amino acid is

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

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

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

Question-44. The pyrenoids are made up of

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

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

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

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

Question-47. Two free ribonucleotide units are interlinked with

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

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

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

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

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

Question-50. Which group contains biocatalysts?

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

Question-51. Which is an essential amino acid?

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

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

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

Question-53. Which is wrong about nucleic acids?

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

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

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

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

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

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

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

Question-57. An enzyme brings about

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

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

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

Question-59. Oils are rich in

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