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Cellular biomolecules and enzymes: NEET MCQs with answers

109 questions on this topic of Cell Structure and Function (NEET 2027 syllabus). Here are 12; tap one to see its answer and explanation.

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easy

1. Identify the basic amino acid from the following options:

  1. Glutamic acid
  2. Valine
  3. Lysine
  4. Aspartic acid
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Answer: (C) Lysine

Lysine is a basic amino acid because it has an additional amino group in its side chain. Glutamic acid and aspartic acid are acidic amino acids, while valine is a neutral amino acid.

medium

2. Lecithin is an example of:

  1. A phospholipid
  2. A polysaccharide
  3. An amino acid
  4. A nucleotide
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Answer: (A) A phospholipid

Some lipids have phosphorous and a phosphorylated organic compound; these are phospholipids, found in cell membranes, e.g. lecithin.

hard

3. Lipids have molecular weights not exceeding 800 Da, yet they appear in the acid-insoluble (macromolecular) fraction because:

  1. They are polymers of glucose
  2. When the tissue is ground, cell membranes are broken into pieces that form water-insoluble vesicles
  3. They bind to nucleic acids
  4. They are very large proteins
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Answer: (B) When the tissue is ground, cell membranes are broken into pieces that form water-insoluble vesicles

Lipids are not strictly macromolecules; membrane fragments form vesicles that separate with the acid-insoluble pool.

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4. Concanavalin A is an example of a secondary metabolite belonging to the category:

  1. Terpenoids
  2. Alkaloids
  3. Lectins
  4. Toxins
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Answer: (C) Lectins

Lectins include concanavalin A; alkaloids include morphine and codeine; toxins include abrin and ricin; drugs include vinblastin and curcumin.

easy

5. Match the protein listed in Column I with its specific physiological function given in Column II: Column I: (A) Collagen (B) Trypsin (C) Insulin (D) Antibody Column II: (i) Hormone (ii) Intercellular ground substance (iii) Fights infectious agents (iv) Enzyme

  1. A-(iii), B-(iv), C-(i), D-(ii)
  2. A-(ii), B-(i), C-(iv), D-(iii)
  3. A-(iv), B-(ii), C-(i), D-(iii)
  4. A-(ii), B-(iv), C-(i), D-(iii)
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Answer: (D) A-(ii), B-(iv), C-(i), D-(iii)

According to NCERT Table 9.5, Collagen acts as an intercellular ground substance, Trypsin is a digestive enzyme, Insulin is a peptide hormone, and Antibody fights infectious agents. Thus, the correct sequence is A-(ii), B-(iv), C-(i), D-(iii).

hard

6. Which of the following is a nucleoside?

  1. Adenylic acid
  2. Adenosine
  3. Adenine
  4. Uridylic acid
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Answer: (B) Adenosine

A nitrogen base attached to a sugar is a nucleoside (adenosine, guanosine, thymidine, uridine, cytidine); with a phosphate it becomes a nucleotide (adenylic acid etc.).

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7. Read the following four statements (A-D) regarding proteins: (A) In an aqueous medium, proteins exist mostly in a globular form where hydrophobic R groups are buried inside. (B) The primary structure of a protein confers upon it a positional information of amino acids. (C) Proteins show only right-handed helices in the secondary structure. (D) A protein consists entirely of a single polypeptide folded into secondary and tertiary structures. How many of the above statements are correct according to NCERT?

  1. One
  2. Two
  3. Three
  4. Four
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Answer: (C) Three

Statements (A), (B), and (C) are correct according to NCERT; NCERT states that in proteins, only right-handed helices are observed. Statement (D) is incorrect because proteins can be composed of one or more polypeptide chains (e.g., hemoglobin has four subunits). Thus, exactly three statements are correct.

easy

8. Which of the following secondary metabolites is correctly paired with its category according to NCERT?

  1. Abrin – Drug
  2. Codeine – Alkaloid
  3. Vinblastin – Alkaloid
  4. Concanavalin A – Toxin
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Answer: (B) Codeine – Alkaloid

According to the secondary metabolites table in NCERT, codeine and morphine are alkaloids. Vinblastin and curcumin are drugs, abrin and ricin are toxins, and concanavalin A is a lectin.

easy

9. Glycerol is a simple lipid. What is its correct chemical IUPAC name?

  1. 1,3-dihydroxy propane
  2. Dihydroxy acetone
  3. Trihydroxy propane (propane-1,2,3-triol)
  4. Propane-1,2-diol
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Answer: (C) Trihydroxy propane (propane-1,2,3-triol)

Glycerol is chemically trihydroxy propane, containing three hydroxyl groups attached to a three-carbon propane chain (propane-1,2,3-triol).

easy

10. The most abundant protein in the whole biosphere is:

  1. Insulin
  2. Collagen
  3. Haemoglobin
  4. RuBisCO
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Answer: (D) RuBisCO

RuBisCO (ribulose bisphosphate carboxylase-oxygenase) is the most abundant protein in the biosphere. Collagen is the most abundant protein in the animal world.

NCERT Class 11

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11. Amino acids are substituted methanes. The four groups occupying the valency positions of the alpha carbon are:

  1. Two carboxyl groups and two amino groups
  2. Phosphate, sugar, base and hydrogen
  3. Glycerol and three fatty acids
  4. Hydrogen, carboxyl group, amino group and a variable R group
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Answer: (D) Hydrogen, carboxyl group, amino group and a variable R group

An amino acid has hydrogen, a carboxyl group, an amino group and a variable R group on the alpha carbon. The nature of R determines the type of amino acid.

NCERT Class 11

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12. Match Column-I with Column-II. Column-I: (A) Oxidoreductases (B) Transferases (C) Hydrolases (D) Isomerases Column-II: (i) Transfer of a group other than hydrogen between substrates (ii) Inter-conversion of optical, geometric or positional isomers (iii) Hydrolysis of ester, ether, peptide and glycosidic bonds (iv) Oxidation–reduction between two substrates

  1. A-(iv), B-(iii), C-(i), D-(ii)
  2. A-(i), B-(iv), C-(iii), D-(ii)
  3. A-(iv), B-(i), C-(iii), D-(ii)
  4. A-(ii), B-(i), C-(iii), D-(iv)
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Answer: (C) A-(iv), B-(i), C-(iii), D-(ii)

Oxidoreductases catalyse redox reactions, transferases transfer groups, hydrolases hydrolyse bonds, and isomerases inter-convert isomers.

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