Biomolecules MCQ For NEET

Biomolecules

Question 1. Sucrose on hydrolysis gives

1. β-D-glucose + α-D-fructose
2. α-D-glucose + β-D-glucose
3. α-D-glucose + β-D-fructose
4. α-D-fructose + β-D-fructose.

Answer: 3. α-D-glucose + β-D-fructose

In sucrose, two monosaccharides are held together by a glycosidic linkage between C-1 of α-D-glucose and C-2 of β-D-fructose.

Sucrose \(\underrightarrow{\text { Hydrolysis }}\) \(\alpha \text { – } D \text {-glucose }+\beta \text { – } D \text {-fructose }\)

Question 2. The difference between amylose and amylopectin is

1. Amylopectin have 1 → 4 α-linkage and 1 → 6 α-linkage
2. Amylose has 1 → 4 α-linkage and 1 → 6 β-linkage
3. Amylopectin have 1 →4 α-linkage and 1 → 6 β-linkage
4. Amylose is made up of glucose and galactose.

Answer: 1. Amylopectin have 1 → 4 α-linkage and 1 → 6 α-linkage

Amylose is a linear polymer of α-D-glucose held by C₁-C₄ glycosidic linkage whereas amylopectin is a branched chain polymer of α-D-glucose units in which the chain is held by C₁-C₄ glycosidic linkage while branching occurs by C₁-C₆ glycosidic linkage.

Question 3. The correct corresponding order of names of four aldoses with the configuration given below respectively, is

1. L-erythrose, L-threose, L-erythrose, D-threose
2. D-threose, D-erythrose, L-threose, L-erythrose
3. L-erythrose, L-threose, D-erythrose, D-threose
4. D-erythrose, D-threose, L-erythrose, L-threose.

Answer: 4. D-erythrose, D-threose, L-erythrose, L-threose.

Question 4. Which one given below is a non-reducing sugar?

1. Glucose
2. Sucrose
3. Maltose
4. Lactose

Answer: 2. Sucrose

All monosaccharides whether aldoses or ketoses are reducing sugars. Disaccharides such as sucrose in which the two monosaccharide units are linked through their reducing centres Le., aldehydic or ketonic groups are non-reducing.

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Quetsion 5. D(+)-glucose reacts with hydroxyl amine and yields an oxime. The structure of the oxime would be

Answer: 4

Question 6. Which one of the following sets of monosaccharides forms sucrose?

1. α-D-galactopyranose and α-D-glucopyranose
2. α-D-glucopyranose and β-D-fructofuranose
3. β-D-glucopyranose and α-D-fructofuranose
4. α-D-glucopyranose and β-D- fructopyranose

Answer: 2. α-D-glucopyranose and β-D fructofuranose

Sucrose is formed by the condensation of α-D- glucopyranose and β-D-fructofuranose.

Question 7. Which one of the following statements is not true regarding (+)-lactose?

1. On hydrolysis (+)-lactose gives equal amounts of D(+)-glucose and D(+)-galactose.
2. (+)-Lactose is a β-glucoside formed by the union of a molecule of D(+)-glucose and a molecule of D(+)-galactose.
3. (+)-Lactose is a reducing sugar and does not exhibit mutarotation.
4. (+)-Lactose, C₁₂H₂₂O₁₁ contains 8 -OH groups

Answer: 3. (+)-Lactose is a reducing sugar and does not exhibit mutarotation.

(+)-Lactose is a reducing sugar and all reducing sugars show mutarotation.

Question 8. Which one of the following does not exhibit the phenomenon of mutarotation?

1. (+)-Sucrose
2. (+)-Lactose
3. (+)-Maltose
4. (-)-Fructose

Answer: 1. (+)-Sucrose

Sucrose does not show mutarotation.

Mutarotation is the phenomenon of change in optical rotation shown by freshly prepared solutions of sugars. However, this property is not exhibited by all sugars.

Only those sugars which have a free aldehyde (-CHO) or ketone (C=O) group aldehyde are capable of ketone of the group showing and is therefore, incapable of showing mutarotation.

Question 9. Fructose reduces Tollens reagent due to

1. Asymmetric carbons
2. Primary alcoholic group
3. Secondary alcoholic group
4. Embolisation of fructose followed by conversion to aldehyde by base.

Answer: 4. Enolisation of fructose followed by conversion to aldehyde by base.

Under alkaline conditions of the reagent, fructose gets converted into a mixture of glucose and mannose (Lobry de Bruyn van Ekenstein rearrangement) both of which contain the -CHO group and hence, reduce Tollens’reagent to give silver mirror test

Question 10. The number of chiral carbons in β-D-(+) glucose is

1. Five
2. Six
3. Three
4. Four.

Answer: 4. Four.

This structure of β-D-glucose has four asymmetric carbon atoms.

Question 11. Glycolysis is

1. Oxidation of glucose to glutamate
2. Conversion of pyruvate to citrate
3. Oxidation of glucose to pyruvate
4. Conversion of glucose to haem

Answer: 3. Oxidation of glucose to pyruvate

Glycolysis is the first stage in the oxidation of glucose. It is an anaerobic process and involves the degradation of glucose into two molecules of pyruvate with the generation of two molecules of ATP.

Question 12. Cellulose is a polymer of

1. Glucose
2. Fructose
3. Ribose
4. Sucrose.

Answer: 1. Glucose

Cellulose is a straight-chain polysaccharide composed of β-D-glucose units joined by β-glycosidic linkage between C₁ of one glucose unit and C₄ of the next glucose unit.

Question 13. Which of the following gives a positive Fehling solution test?

1. Sucrose
2. Glucose
3. Fats
4. Protein

Answer: 2. Glucose

Glucose reduces Fehling solution because glucose has a free -CHO group which is readily oxidised.

Question 14. α-D-glucose and β-D-glucose are

1. Epimers
2. Anomers
3. Enantiomers
4. Diastereomers.

Answer: 2. Anomers

Glucose forms a stable hemiacetal between the -CHO group and the -OH group on the 5th carbon. In this process, the 1st ‘C’ atom becomes asymmetric giving two isomers which differ in the configuration of the asymmetric carbon. These two isomers are called anomers.

Question 15. Which of the following is the sweetest sugar?

1. Fructose
2. Glucose
3. Sucrose
4. Maltose

Answer: 1. Fructose

Fructose is the sweetest among all the sugars and is highly soluble in water.

Question 16. Glucose molecule reacts with X number of molecules of phenylhydrazine to yield osazone. The value of X is (8)

1. Two
2. Three
3. Four
4. Five

Answer: 4. Five

Glucose first reacts with phenyl hydrazine giving phenylhydrazine. Then the adjacent -CHOH group is oxidized by a 2d phenyl hydrazine molecule and itself is reduced to aniline. The resulting carbonyl group reacts with 3’d phenyl hydrazine molecule giving osazone.

Question 17. The oxidation of glucose is one of the most important reactions in a living cell. What is the number of ATP molecules generated in cells from one molecule of glucose?

1. 28
2. 38
3. 12
4. 18

Answer: 2. 38

⇒ \(\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6+6 \mathrm{O}_2 \rightarrow 6 \mathrm{CO}_2+6 \mathrm{H}_2 \mathrm{O}+38 \mathrm{ATP}\)

Question 18. The α-D-glucose and β-D-glucose differ from each other due to differences in carbon atoms with respect to its

1. Number of OH groups
2. Size of hemiacetal ring
3. Conformation
4. Configuration.

Answer: 4. Configuration.

These isomers differ only in the orientation (or configuration) of the Cl atom.

Question 19. Chemically considering digestion is basically

1. Anabolism
2. Hydrogenation
3. Hydrolysis
4. Dehydrogenation.

Answer: 3. Hydrolysis

Question 20. On hydrolysis of starch, we finally get

1. Glucose
2. Fructose
3. Both (1) and (2)
4. Sucrose.

Answer: 1. Glucose

Glucose is produced commercially by the hydrolysis of starch by boiling it with dil. H₂SO₄ at 393 K under pressure of 2-3 bar.

Question 21. Which of the following is a basic amino acid?

1. Serine
2. Alanine
3. Tyrosine
4. Lysine

Answer: 4. Lysine

Lysine is a basic amino acid

Question 22. The non-essential amino acids among the following is

1. Lysine
2. Valine
3. Leucine
4. Alanine.

Answer: 4. Alanine

Question 23. Which structure(s) of proteins remains (s) intact during the denaturation process?

1. Both secondary and tertiary structures
2. Primary structure only
3. Secondary structure only
4. Tertiary structure only

Answer: 2. Primary structure only

During the denaturation of Proteins, 2° and 3° structures are destroyed but 1o structure remains intact.

Question 24. Which of the following compounds can form a zwitter ion?

1. Aniline
2. Acetanilide
3. Benzoic acid
4. Glycine

Answer: 4. Glycine

⇒ \(\mathrm{HOOC}-\underset{\text { Glycine }}{\mathrm{CH}_2-} \mathrm{NH}_2 \rightleftharpoons-\mathrm{OOC} \underset{\text { Zwitter ion }}{\mathrm{CH}_2}-\stackrel{+}{\mathrm{N}} \mathrm{H}_3\)

Question 25. In a protein molecule, various amino acids are linked together by

1. Peptide bond
2. Dative bond
3. α-glycosidic bond
4. β-Glycosidic bond.

Answer: 1. Peptide bond

Question 26. Which of the statements about “Denaturation” given below are correct?

1. Denaturation of proteins causes loss of secondary and tertiary structures of the protein.
2. Denaturation leads to the conversion of a double strand of DNA into a single strand.
3. Denaturation affects the primary structure which gets distorted.

1. (2) and (3)
2. (1) and (3)
3. (1) and (2)
4. (1), (2) and (3)

Anbswer: 3. (1) and (2)

Denaturation does not change the primary structure of the protein.

Question 27. Which functional group participates in disulphide bond formation in proteins?

1. Thioester
2. Thioether
3. Thiol
4. Thiolactone

Answer: 3. Thiol

Disulphide bond may be reduced to thiol by means of reagents i.e., NaBH₄, which shows the presence of thiol group in disulphide bond formation.

Question 28. Which of the following structures represents the peptide chain?

Answer: 3

In peptide linkage i.e., – CONH – group, the carboxyl group of one amino acid molecule forms an amide by combination with the amino group of the next amino acid molecule with the liberation of a water molecule.

Question 29. The correct statement in respect to protein haemoglobin is that it

1. Functions as a catalyst for biological reactions
2. Maintains blood sugar level
3. Acts as an oxygen carrier in the blood
4. Forms antibodies and offers resistance to diseases.

Answer: 3. Acts as an oxygen carrier in the blood

Four Fe²⁺ ions of each haemoglobin can bind with four molecules of O₂ and it is carried as oxyhaemoglobin.

Question 30. The helical structure of protein is stabilised by

1. Dipeptide Bonds
2. Hydrogen Bonds
3. Ether Bonds
4. Peptide Bonds.

Answer: 2. Hydrogen Bonds

α-Hellt structure is formed when the chain of α-amino acids coil as a right-handed screw because of the formation of hydrogen bonds between amide groups of the same peptide chain, i.e., NH group in one unit is linked to carbonyl oxygen of the fourth unit by hydrogen bonding. This H-trending is responsible for holding the helix in a stable position.

Question 31. Which is not a true statement?

1. α-Carbon of α-amino acid is asymmetric.
2. All proteins are found in the L-form.
3. The human body can synthesise all the proteins it needs.
4. At pH = 7, both ammo and carboxylic small groups exist in ionised form.

Answer: 2. All proteins are found in L-form

Some proteins are also found in the D-form.

Quetsion 32. (peptide bond)

Which statement is incorrect about peptide bonds?

1. The C – N bond length in proteins is longer than the usual bond length of the N – C bond.
2. Spectroscopic analysis shows the planar structure of the   group.
3. The C – N bond length in proteins is smaller than the usual bond length of the C – N bond.
4. None of the above.

Answer: 1. The C – N bond length in proteins is longer than the usual bond length of the N – C bond.

A Peptide bond is formed by the reaction of the -COOH group of one amino acid with the -NH₃ group of another amino acid and is represented as

As some double bond character is found between C-N bonds, the bond length of C-N in protein should be smaller than the usual C-N bond.

Question 33. Which is the correct statement?

1. Starch is a polymer of α-glucose.
2. Amylose is a component of cellulose.
3. Proteins are composed of only one type of amino acid.
4. In the cyclic structure of fructose, there are four carbons and one oxygen atom.

Answer: 1. Starch is a polymer of α-glucose.

Starch is also known as amylum which occurs in all green plants. A molecule of starch (C₆H₁₀O₅)_n is built of a large number of α-glucose rings joined through oxygen atoms.

Question 34. Haemoglobin is

1. A Vitamin
2. A Carbohydrate
3. An Enzyme
4. A Globular Protein.

Answer: 4. A Globular Protein.

Haemoglobin is a globular protein of four subunits, each subunit having a heme moiety and a polypeptide chain (Two α and two β chains).

Question 35. The secondary structure of a protein refers to

1. Regular folding patterns of continuous portions of the polypeptide chain
2. Three-dimensional structure, especially the bond between amino acid residues that are distant from each other in the polypeptide chain
3. Mainly denatured proteins and structures of prosthetic groups
4. Linear sequence of amino acid residues in the polypeptide chain.

Answer: 1. Regular folding patterns of continuous portions of the polypeptide chain

Question 36. During the process of digestion, the proteins present in food materials are hydrolysed to amino acids. The two enzymes involved in the process proteins \(\underrightarrow{\text { enzyme }(A)}\) polypeptides \(underrightarrow{\text { enzyme }(B)}\) amino acids, are respectively.

1. Invertase and zymase
2. Amylase and maltase
3. Diastase and lipase
4. Pepsin and trypsin

Answer: 4. Pepsin and trypsin

Question 37. Enzymes are made up of

1. Edible proteins
2. Proteins with specific structure
3. Nitrogen-containing carbohydrates
4. Carbohydrates.

Answer: 2. Proteins with specific structure

Question 38. Which of the following is correct?

1. Cycloheptane is an aromatic compound.
2. Diastase is an enzyme.
3. Acetophenone is an ether.
4. All of these.

Answer: 2. Diastase is an enzyme.

Diastase is an enzyme that hydrolyses starch into maltose

Question 39. The function of enzymes in the living system is to

1. Catalyse biochemical reactions
2. Provide energy
3. Transport oxygen
4. Provide immunity.

Answer: 1. Catalyse biochemical reactions

Question 40. Which of the following statements about enzymes is true?

1. Enzymes catalyse chemical reactions by increasing the activation energy.
2. Enzymes are highly specific both in binding chiral substrates and in catalysing their reactions.
3. Enzymes lack in nucleophilic groups.
4. Pepsin is a proteolytic enzyme.

Answer: 4. Pepsin is a proteolytic enzyme.

Question 41. Enzymes take part in a reaction and

1. Decrease the rate of a chemical reaction
2. Increase the rate of a chemical reaction
3. Both (1) and (2)
4. None of these.

Answer; 2. Increase the rate of a chemical reaction

Enzyrnes being a biocatalyst increases the rate of a chemical reaction by providing alternative lower activation energy pathways.

Question 42. RBC deficiency is a deficiency disease of

1. Vitamin B₂
2. Vitamin B₁₂
3. Vitamin B₆
4. Vitamin B₁

Answer: 2. Vitamin B₁₂

Anaemia is a disease in which the body does not have enough red blood cells (RBC) due to a lack of vitamin B-12. This vitamin is needed to make red blood cells.

Question 43. A deficiency of vitamin B₁ causes the disease

1. Convulsions
2. Beriberi
3. Cheilosis
4. Sterility.

Answer: 2. Beri-beri

Question 44. Which of the following is not a fat-soluble vitamin?

1. Vitamin B complex
2. Vitamin D
3. Vitamin E
4. Vitamin A

Answer: 1. Vitamin B complex

Vitamin B complex is not a fat-soluble vitamin. It is a water-soluble vitamin.

Question 45. Which of the following vitamins is water soluble?

1. Vitamin E
2. Vitamin K
3. Vitamin A
4. Vitamin B

Answer: 4. Vitamin B

Vitamins B and C are water soluble whereas vitamins A, D, E and K are fat soluble

Question 46. The human body does not produce

1. Enzymes
2. DNA
3. Vitamins
4. Hormones.

Answer: 3. Vitamins

Certain organic substances required for regulating some of the body processes and preventing certain diseases are called vitamins, which cannot be synthesised by the human body.

Question 47. Vitamin B₁₂ contains

1. Fe (2)
2. Co (3)
3. Zn (2)
4. Ca (2)

Answer: 2. Co (3)

Vitamin B₁₂ is chemically named a cyanocobalamin having molecular formula C₆₃H₈₈O₁₄N₁₄PCo.

Question 48. Given below are two statements.

• Statement 1: A unit formed by the attachment of a base to 1′-position of sugar is known as a nucleoside.
• Statement 2: When nucleoside is linked to phosphorous acid at the 5′-position of the sugar moiety, we get nucleotide.

In light of the above statements, choose the correct answer from the options given below.

1. Statement 1 is true but Statement 2 is false.
2. Statement 1 is false but Statement 2 is true.
3. Both Statement 1 and Statement 2 are true.
4. Both Statement 1 and Statement 2 are false.

Answer: 1. Statement 1 is true but Statement 2 is false.

When nucleoside is linked to phosphoric acid (not phosphorous acid) at the 5′-position of the sugar moiety, we get nucleotide.

Question 49. The central dogma of molecular genetics states that genetic information flows from

1. Amino acids → Proteins → DNA
2. DNA → Carbohydrates → Proteins
3. DNA → RNA → Proteins
4. DNA → RNA → Carbohydrates

Answer: 3. DNA → RNA → Proteins

Genetic information flows from

DNA \(\underrightarrow{\text { Transcription }}\) RNA \(\underrightarrow{\text { Translation }}\) Proteins

Quetsion 50. The correct statement regarding RNA and DNA, respectively is

1. The sugar component in RNA is arabinose and the sugar component in DNA is ribose
2. The sugar component in RNA is 2′-deoxyribose and the sugar component in DNA is arabinose
3. The sugar component in RNA is arabinose and the sugar component in DNA is 2′-deoxyribose
4. The sugar component in RNA is ribose and the sugar component in DNA is 2′-deoxyribose.

Answer: 4. The sugar component in RNA is ribose and the sugar component in DNA is 2′-deoxyribose.

Question 51. In DNA, the linkages between different nitrogenous bases are

1. Phosphate linkage
2. H-bonding
3. Glycosidic linkage
4. Peptide linkage.

Answer: 2. H-bonding

Nitrogenous bases are linked together by hydrogen bonds.

Question 52. The segment of DNA which acts as the instrumental manual for the synthesis of the protein is

1. Ribose
2. Gene
3. Nucleoside
4. Nucleotide.

Answer: 2. Gene

Genes are responsible for protein synthesis.

Question 53. In DNA, the complementary bases are

1. Adenine and guanine; thymine and cytosine
2. Uracil and adenine; cytosine and guanine
3. Adenine and thymine; guanine and cytosine
4. Adenine and thymine; guanine and uracil

Answer: 3. Adenine and thymine; guanine and cytosine

DNA contains two types of nitrogenous bases

Purine → Adenine (A) and guanine (G)

Pyrimidine → Cytosine (C) and thymine (T)

The purine and pyrimidine bases pair only in certain combinations. Adenine pairs with thymine (A:T) by two hydrogen bonds and guanine with cytosine (G: C) by three hydrogen bonds.

Question 54. RNA and DNA are chiral molecules, their chirality is due to

1. Chiral bases
2. Chiral phosphate ester units
3. D-sugar component
4. L-sugar component.

Answer: 3. D-sugar component

The constituents of nucleic acids are nitrogenous bases, sugar and phosphoric acid. The sugar present in DNA is D(-)-2-deoxyribose and the sugar present in RNA is D(-)- ribose. Due to these D(-)-sugar components, DNA and RNA molecules are chiral molecules.

Question 55. A sequence of how many nucleotides in messenger RNA makes a codon for an amino acid?

1. Three
2. Four
3. One
4. Two

Answer: 1. Three

The four bases in mRNA: adenine, cytosine, guanine and uracil have been shown to act in the form of triplets; each triplet behaving as a code for the synthesis of a particular amino acid

Question 56. Chargaff’s rule states that in an organism

1. The amount of adenine (A) is equal to that of thymine (T) and the amount of guanine (G) is equal to that of cytosine (C)
2. The amount of adenine (A) is equal to that of guanine (G) and the amount of thymine (T) is equal to that of cytosine (C)
3. The amount of adenine (A) is equal to that of cytosine (C) and the amount of thymine(T) is equal to that of guanine (G)
4. Amounts of all bases are equal.

Answer: 1. Amount of adenine (A) is equal to that of thymine (T) and the amount of guanine (G) is equal to that of cytosine (C)

Amount of A = T and that of G = C

Question 57. Which of the following is correct about H-bonding in nucleotide?

1. A – T, G – C
2. A – G, T – C
3. G – T, A – C
4. A – A, T – T

Answer: 1. A – T, G – C

Question 58. An example of a biopolymer is

1. Teflon
2. Neoprene
3. Nylon-6,6
4. DNA.

Answer: 4. DNA.

DNA is an example of a biopolymer

Question 59. The couplings between base units of DNA is through 

1. Hydrogen bonding
2. Electrostatic bonding
3. Covalent bonding
4. Van der Waal’s forces

Answer: 1. Hydrogen bonding

Question 60. Which of the following statements is not correct?

1. Ovalbumin is a simple food reserve in egg whites.
2. Blood proteins thrombin and fibrinogen are involved in blood clotting.
3. Denaturation makes the proteins more active.
4. Insulin maintains sugar levels in the blood of the human body.

Answer: 3. Denaturation makes the proteins more active.

Question 61. Which of the following hormones is produced under the conditions of stress which stimulate glycogenolysis in the liver of human beings?

1. Thyroxin
2. Insulin
3. Adrenaline
4. Estradiol

Answer: 3. Adrenaline

Adrenaline hormone helps to release fatty acids from fat and glucose from liver glycogen under the condition of stress. Hence, it is also called flight or fight hormone.

Question 62. Which of the following hormones contains iodine?

1. Testosterone
2. Adrenaline
3. Thyroxine
4. Insulin

Answer: 3. Thyroxine

Question 63. Which of the following is an amine hormone?

1. Insulin
2. Progesterone
3. Thyroxine
4. Oxypurin

Answer: 3. Thyroxine

Thyroxine is an amine hormone and water-soluble hormone containing an amino group.

Question 64. Which one of the following is a peptide hormone?

1. Adrenaline
2. Glucagon
3. Testosterone
4. Thyroxine

Answer: 2. Glucagon

Glucagon is a peptide hormone, synthesised by the a-cells of the pancreas.

Question 65. The hormone that helps in the conversion of glucose to glycogen is

1. Cortisone
2. Bile acids
3. Adrenaline
4. Insulin.

Answer: 4. Insulin

Insulin is a hormone secreted by the pancreas that lowers blood glucose levels by promoting the uptake of glucose by cells and the conversion of glucose to glycogen by the liver and skeletal muscle

Question 66. Which one is responsible for the production of energy in biochemical reactions?

1. Thyroxine
2. Adrenaline
3. Oestrogen
4. Progesterone

Answer: 1. Thyroxine

It is a hormone secreted from the thyroid gland. It controls various biochemical reactions involving the burning of proteins, carbohydrates, and fats to release energy.

Question 67. The cell membranes are mainly composed of

1. Fats
2. Proteins
3. Phospholipids
4. Carbohydrates.

Answer: 3. Phospholipids

Cell membranes are mainly composed of phospholipids.

Question 68. Phospholipids are esters of glycerol with

1. Three carboxylic acid residues
2. Two carboxylic acid residues and one phosphate group
3. One carboxylic acid residue and two phosphate groups
4. Three phosphate groups

Answer: 2. Two carboxylic acid residues and one phosphate group

Phospholipids may be regarded as derivatives of glycerol in which two of the hydroxy groups are esterified with fatty acids while the third is esterified with some derivatives of phosphoric acid.

Question 69. The number of molecules of ATP produced in the lipid metabolism of a molecule of palmitic acid is

1. 56
2. 36
3. 130
4. 86

Answer: 3. 130

In lipid metabolism, a molecule of palmitic acid (C₁₅H₃₁ – COOH) produces 130 adenosine triphosphate molecules (ATP).