Complete Biomolecules Question Bank & Solutions (70 Questions)
Q1 of 70
NEET NCERT Line-by-Line
Biomolecules are separated into pools using:
(A)
Hydrochloric acid
(B)
Trichloroacetic acid
(C)
Sulphuric acid
(D)
Acetic acid
Show Answer & NCERT Explanation
Correct Answer: (B) Trichloroacetic acid
Tissue is ground in trichloroacetic acid and filtered.
Q2 of 70
NEET NCERT Line-by-Line
The acid-soluble pool contains:
(A)
Proteins
(B)
Nucleic acids
(C)
Micromolecules like amino acids
(D)
Polysaccharides
Show Answer & NCERT Explanation
Correct Answer: (C) Micromolecules like amino acids
Small biomolecules (~18–800 Da) are acid-soluble.
Q3 of 70
NEET NCERT Line-by-Line
'Ash' obtained after burning tissue represents:
(A)
Proteins
(B)
Inorganic elements
(C)
Lipids
(D)
Water
Show Answer & NCERT Explanation
Correct Answer: (B) Inorganic elements
Ash is the inorganic residue after C, H, O leave as gases.
Q4 of 70
NEET NCERT Line-by-Line
The most abundant molecule in a living organism is:
(A)
Protein
(B)
Glucose
(C)
Water
(D)
DNA
Show Answer & NCERT Explanation
Correct Answer: (C) Water
Water is the most abundant molecule in living things.
Q5 of 70
NEET NCERT Line-by-Line
Compared with the Earth's crust, living matter is especially rich in:
(A)
Silicon and aluminium
(B)
Carbon, hydrogen, oxygen, nitrogen
(C)
Iron and sulphur
(D)
Sodium and chlorine
Show Answer & NCERT Explanation
Correct Answer: (B) Carbon, hydrogen, oxygen, nitrogen
C, H, O and N are enriched in organisms.
Q6 of 70
NEET NCERT Line-by-Line
Alkaloids, rubber and antibiotics are examples of:
(A)
Primary metabolites
(B)
Secondary metabolites
(C)
Macromolecules
(D)
Inorganic ions
Show Answer & NCERT Explanation
Correct Answer: (B) Secondary metabolites
These are secondary metabolites.
Q7 of 70
NEET NCERT Line-by-Line
Each amino acid has a variable component called the:
(A)
Carboxyl group
(B)
Amino group
(C)
R group
(D)
Peptide bond
Show Answer & NCERT Explanation
Correct Answer: (C) R group
The R group (side chain) varies among amino acids.
Q8 of 70
NEET NCERT Line-by-Line
The number of standard amino acids in proteins is:
(A)
4
(B)
16
(C)
20
(D)
64
Show Answer & NCERT Explanation
Correct Answer: (C) 20
There are 20 standard amino acids.
Q9 of 70
NEET NCERT Line-by-Line
In solution, an amino acid exists as a:
(A)
Cation only
(B)
Anion only
(C)
Zwitterion
(D)
Neutral molecule with no charge
Show Answer & NCERT Explanation
Correct Answer: (C) Zwitterion
It is a zwitterion (both + and – charges).
Q10 of 70
NEET NCERT Line-by-Line
The bond between two amino acids is a:
(A)
Glycosidic bond
(B)
Peptide bond
(C)
Phosphodiester bond
(D)
Hydrogen bond
Show Answer & NCERT Explanation
Correct Answer: (B) Peptide bond
Amino acids join by peptide bonds.
Q11 of 70
NEET NCERT Line-by-Line
The R group of glycine is:
(A)
H
(B)
CH₃
(C)
CH₂OH
(D)
C₆H₅
Show Answer & NCERT Explanation
Correct Answer: (A) H
Glycine's R group is a hydrogen atom.
Q12 of 70
NEET NCERT Line-by-Line
A protein is a:
(A)
Homopolymer
(B)
Heteropolymer
(C)
Monomer
(D)
Disaccharide
Show Answer & NCERT Explanation
Correct Answer: (B) Heteropolymer
Proteins are heteropolymers of different amino acids.
Q13 of 70
NEET NCERT Line-by-Line
The most abundant protein in the animal world is:
(A)
RuBisCO
(B)
Collagen
(C)
Insulin
(D)
Haemoglobin
Show Answer & NCERT Explanation
Correct Answer: (B) Collagen
Collagen is most abundant in the animal world.
Q14 of 70
NEET NCERT Line-by-Line
The most abundant protein in the whole biosphere is:
(A)
Collagen
(B)
Keratin
(C)
RuBisCO
(D)
Albumin
Show Answer & NCERT Explanation
Correct Answer: (C) RuBisCO
RuBisCO is the most abundant protein in the biosphere.
Q15 of 70
NEET NCERT Line-by-Line
The sequence of amino acids in a protein is its:
(A)
Primary structure
(B)
Secondary structure
(C)
Tertiary structure
(D)
Quaternary structure
Show Answer & NCERT Explanation
Correct Answer: (A) Primary structure
Amino-acid sequence = primary structure.
Q16 of 70
NEET NCERT Line-by-Line
Haemoglobin's four-subunit organisation illustrates:
(A)
Primary structure
(B)
Secondary structure
(C)
Tertiary structure
(D)
Quaternary structure
Show Answer & NCERT Explanation
Correct Answer: (D) Quaternary structure
Multiple chains (2α + 2β) = quaternary structure.
Q17 of 70
NEET NCERT Line-by-Line
Monosaccharides are joined in polysaccharides by:
(A)
Peptide bonds
(B)
Glycosidic bonds
(C)
Ester bonds
(D)
Phosphodiester bonds
Show Answer & NCERT Explanation
Correct Answer: (B) Glycosidic bonds
Glycosidic bonds link sugars.
Q18 of 70
NEET NCERT Line-by-Line
Which polysaccharide gives a blue-black colour with iodine?
(A)
Cellulose
(B)
Starch
(C)
Glycogen
(D)
Chitin
Show Answer & NCERT Explanation
Correct Answer: (B) Starch
Starch's helix traps iodine (blue-black).
Q19 of 70
NEET NCERT Line-by-Line
Cellulose is best described as a:
(A)
Branched glucose polymer
(B)
Homopolymer of glucose
(C)
Polymer of fructose
(D)
Polymer of amino sugars
Show Answer & NCERT Explanation
Correct Answer: (B) Homopolymer of glucose
Cellulose is a homopolymer of glucose.
Q20 of 70
NEET NCERT Line-by-Line
The animal storage polysaccharide is:
(A)
Starch
(B)
Cellulose
(C)
Glycogen
(D)
Inulin
Show Answer & NCERT Explanation
Correct Answer: (C) Glycogen
Glycogen is the branched animal store.
Q21 of 70
NEET NCERT Line-by-Line
Inulin is a polymer of:
(A)
Glucose
(B)
Fructose
(C)
Galactose
(D)
Ribose
Show Answer & NCERT Explanation
Correct Answer: (B) Fructose
Inulin is a fructose polymer.
Q22 of 70
NEET NCERT Line-by-Line
Chitin is found in:
(A)
Plant cell walls only
(B)
Arthropod exoskeletons and fungal walls
(C)
Bone matrix
(D)
Blood plasma
Show Answer & NCERT Explanation
Correct Answer: (B) Arthropod exoskeletons and fungal walls
Chitin occurs in arthropod exoskeletons and fungal walls.
Q23 of 70
NEET NCERT Line-by-Line
Palmitic acid contains how many carbons?
(A)
14
(B)
16
(C)
18
(D)
20
Show Answer & NCERT Explanation
Correct Answer: (B) 16
Palmitic acid has 16 carbons.
Q24 of 70
NEET NCERT Line-by-Line
Arachidonic acid contains how many carbons?
(A)
16
(B)
18
(C)
20
(D)
22
Show Answer & NCERT Explanation
Correct Answer: (C) 20
Arachidonic acid has 20 carbons.
Q25 of 70
NEET NCERT Line-by-Line
Glycerol is chemically:
(A)
Trihydroxy propane
(B)
A fatty acid
(C)
A hexose
(D)
An amino acid
Show Answer & NCERT Explanation
Correct Answer: (A) Trihydroxy propane
Glycerol = trihydroxy propane.
Q26 of 70
NEET NCERT Line-by-Line
Lecithin is an example of a:
(A)
Triglyceride
(B)
Phospholipid
(C)
Steroid
(D)
Wax
Show Answer & NCERT Explanation
Correct Answer: (B) Phospholipid
Lecithin is a membrane phospholipid.
Q27 of 70
NEET NCERT Line-by-Line
A nucleoside is composed of:
(A)
Base + sugar
(B)
Base + phosphate
(C)
Sugar + phosphate
(D)
Base + sugar + phosphate
Show Answer & NCERT Explanation
Correct Answer: (A) Base + sugar
Nucleoside = base + sugar; adding phosphate gives a nucleotide.
Q28 of 70
NEET NCERT Line-by-Line
Which of these are purines?
(A)
Cytosine and Thymine
(B)
Adenine and Guanine
(C)
Uracil and Cytosine
(D)
Thymine and Uracil
Show Answer & NCERT Explanation
Correct Answer: (B) Adenine and Guanine
Purines = adenine and guanine.
Q29 of 70
NEET NCERT Line-by-Line
Which base is found in RNA but not DNA?
(A)
Adenine
(B)
Thymine
(C)
Uracil
(D)
Guanine
Show Answer & NCERT Explanation
Correct Answer: (C) Uracil
RNA has uracil; DNA has thymine.
Q30 of 70
NEET NCERT Line-by-Line
Nucleotides in a strand are joined by:
(A)
Peptide bonds
(B)
Glycosidic bonds
(C)
Phosphodiester bonds
(D)
Hydrogen bonds
Show Answer & NCERT Explanation
Correct Answer: (C) Phosphodiester bonds
Phosphodiester bonds link nucleotides.
Q31 of 70
NEET NCERT Line-by-Line
Adenine pairs with thymine through how many hydrogen bonds?
Show Answer & NCERT Explanation
Correct Answer: (B) 2
A–T forms 2 hydrogen bonds.
Q32 of 70
NEET NCERT Line-by-Line
Guanine pairs with cytosine through how many hydrogen bonds?
Show Answer & NCERT Explanation
Correct Answer: (C) 3
G–C forms 3 hydrogen bonds.
Q33 of 70
NEET NCERT Line-by-Line
The two strands of DNA are:
(A)
Parallel
(B)
Antiparallel
(C)
Identical in sequence
(D)
Single-stranded
Show Answer & NCERT Explanation
Correct Answer: (B) Antiparallel
DNA strands are antiparallel.
Q34 of 70
NEET NCERT Line-by-Line
The pitch of the B-DNA helix is:
(A)
3.4 Å
(B)
10 Å
(C)
34 Å
(D)
20 Å
Show Answer & NCERT Explanation
Correct Answer: (C) 34 Å
Pitch = 34 Å (rise per bp is 3.4 Å).
Q35 of 70
NEET NCERT Line-by-Line
The number of base pairs per turn of B-DNA is about:
(A)
5
(B)
10
(C)
20
(D)
34
Show Answer & NCERT Explanation
Correct Answer: (B) 10
About 10 base pairs per turn.
Q36 of 70
NEET NCERT Line-by-Line
Pathways that synthesise complex molecules and consume energy are:
(A)
Catabolic
(B)
Anabolic
(C)
Hydrolytic
(D)
Oxidative
Show Answer & NCERT Explanation
Correct Answer: (B) Anabolic
Anabolic pathways build up and consume energy.
Q37 of 70
NEET NCERT Line-by-Line
The 'energy currency' of the cell is:
(A)
NADP
(B)
Glucose
(C)
ATP
(D)
DNA
Show Answer & NCERT Explanation
Correct Answer: (C) ATP
ATP is the cell's energy currency.
Q38 of 70
NEET NCERT Line-by-Line
Glycolysis converts glucose into:
(A)
Two pyruvic acid molecules
(B)
One acetyl-CoA
(C)
Glycogen
(D)
Citric acid
Show Answer & NCERT Explanation
Correct Answer: (A) Two pyruvic acid molecules
Glucose → 2 pyruvic acid molecules.
Q39 of 70
NEET NCERT Line-by-Line
The living state is described as a:
(A)
Equilibrium state
(B)
Non-equilibrium steady state
(C)
Static state
(D)
Crystalline state
Show Answer & NCERT Explanation
Correct Answer: (B) Non-equilibrium steady state
A non-equilibrium steady state able to do work.
Q40 of 70
NEET NCERT Line-by-Line
At equilibrium, a system can perform:
(A)
Maximum work
(B)
No work
(C)
Only mechanical work
(D)
Only chemical work
Show Answer & NCERT Explanation
Correct Answer: (B) No work
At equilibrium no work is possible (would mean death).
Q41 of 70
NEET NCERT Line-by-Line
RNA molecules that act as enzymes are called:
(A)
Coenzymes
(B)
Ribozymes
(C)
Apoenzymes
(D)
Isozymes
Show Answer & NCERT Explanation
Correct Answer: (B) Ribozymes
Ribozymes are catalytic RNA molecules.
Q42 of 70
NEET NCERT Line-by-Line
Enzymes accelerate reactions by:
(A)
Raising activation energy
(B)
Lowering activation energy
(C)
Changing the products
(D)
Adding heat
Show Answer & NCERT Explanation
Correct Answer: (B) Lowering activation energy
Enzymes lower the activation energy.
Q43 of 70
NEET NCERT Line-by-Line
The substrate binds the enzyme at the:
(A)
Allosteric end
(B)
Active site
(C)
Carboxyl terminal
(D)
Prosthetic group
Show Answer & NCERT Explanation
Correct Answer: (B) Active site
The substrate binds the active site forming the ES complex.
Q44 of 70
NEET NCERT Line-by-Line
Maximum velocity of an enzyme reaction is denoted:
(A)
Km
(B)
Vmax
(C)
ΔG
(D)
pKa
Show Answer & NCERT Explanation
Correct Answer: (B) Vmax
Rate plateaus at Vmax as substrate increases.
Q45 of 70
NEET NCERT Line-by-Line
Malonate inhibits succinic dehydrogenase as a:
(A)
Non-competitive inhibitor
(B)
Competitive inhibitor
(C)
Coenzyme
(D)
Activator
Show Answer & NCERT Explanation
Correct Answer: (B) Competitive inhibitor
Malonate competes with succinate at the active site.
Q46 of 70
NEET NCERT Line-by-Line
Which is NOT one of the six enzyme classes?
(A)
Oxidoreductases
(B)
Hydrolases
(C)
Polymerases
(D)
Ligases
Show Answer & NCERT Explanation
Correct Answer: (C) Polymerases
The six classes are oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases.
Q47 of 70
NEET NCERT Line-by-Line
The protein part of an enzyme without its cofactor is the:
(A)
Holoenzyme
(B)
Apoenzyme
(C)
Coenzyme
(D)
Ribozyme
Show Answer & NCERT Explanation
Correct Answer: (B) Apoenzyme
The protein-only part is the apoenzyme.
Q48 of 70
NEET NCERT Line-by-Line
NAD and NADP contain the vitamin:
(A)
Riboflavin
(B)
Niacin
(C)
Thiamine
(D)
Biotin
Show Answer & NCERT Explanation
Correct Answer: (B) Niacin
NAD and NADP contain niacin.
Q49 of 70
NEET NCERT Line-by-Line
The metal-ion cofactor of carboxypeptidase is:
(A)
Iron
(B)
Magnesium
(C)
Zinc
(D)
Copper
Show Answer & NCERT Explanation
Correct Answer: (C) Zinc
Zinc is the cofactor of carboxypeptidase.
Q50 of 70
NEET NCERT Line-by-Line
Enzymes that catalyse hydrolysis reactions are:
(A)
Lyases
(B)
Hydrolases
(C)
Ligases
(D)
Isomerases
Show Answer & NCERT Explanation
Correct Answer: (B) Hydrolases
Hydrolases break bonds using water.
Q51 of 70
NEET NCERT Line-by-Line
Lipids appear in the acid-INSOLUBLE pool mainly because they:
(A)
Are very small
(B)
Assemble into large membrane structures
(C)
Dissolve in TCA
(D)
Are inorganic
Show Answer & NCERT Explanation
Correct Answer: (B) Assemble into large membrane structures
Though their units are small, lipids form large structures, landing in the macromolecule pool.
Q52 of 70
NEET NCERT Line-by-Line
Which statement about water is correct?
(A)
It is a secondary metabolite
(B)
It is the most abundant molecule in organisms
(C)
It is acid-insoluble
(D)
It is a macromolecule
Show Answer & NCERT Explanation
Correct Answer: (B) It is the most abundant molecule in organisms
Water is the single most abundant molecule in living things.
Q53 of 70
NEET NCERT Line-by-Line
A protein loses biological activity when which level is disrupted?
(A)
Only primary
(B)
Tertiary (3-D shape)
(C)
Quaternary only
(D)
None
Show Answer & NCERT Explanation
Correct Answer: (B) Tertiary (3-D shape)
Activity depends on the precise tertiary 3-D shape.
Q54 of 70
NEET NCERT Line-by-Line
Which pairing of polysaccharide → property is WRONG?
(A)
Starch → forms a helix
(B)
Cellulose → branched storage in animals
(C)
Glycogen → branched
(D)
Inulin → fructose polymer
Show Answer & NCERT Explanation
Correct Answer: (B) Cellulose → branched storage in animals
Cellulose is an unbranched structural homopolymer in plants, not animal storage.
Q55 of 70
NEET NCERT Line-by-Line
Choose the correct base-pair/H-bond combination.
(A)
A–T (3), G–C (2)
(B)
A–T (2), G–C (3)
(C)
A–G (2), T–C (3)
(D)
A–C (2), G–T (3)
Show Answer & NCERT Explanation
Correct Answer: (B) A–T (2), G–C (3)
A–T has 2 H-bonds; G–C has 3.
Q56 of 70
NEET NCERT Line-by-Line
If a B-DNA segment has 20 base pairs, roughly how many helical turns does it span?
(A)
1
(B)
2
(C)
10
(D)
20
Show Answer & NCERT Explanation
Correct Answer: (B) 2
~10 bp per turn → 20 bp ≈ 2 turns.
Q57 of 70
NEET NCERT Line-by-Line
Which set lists only purines?
(A)
A, G
(B)
C, T
(C)
A, U
(D)
G, C
Show Answer & NCERT Explanation
Correct Answer: (A) A, G
Purines are adenine and guanine.
Q58 of 70
NEET NCERT Line-by-Line
An enzyme speeds a reaction by:
(A)
Increasing the energy difference of products
(B)
Lowering activation energy without changing ΔE
(C)
Adding heat to substrate
(D)
Changing the equilibrium constant value of products
Show Answer & NCERT Explanation
Correct Answer: (B) Lowering activation energy without changing ΔE
It lowers the activation-energy barrier; overall ΔE is unchanged.
Q59 of 70
NEET NCERT Line-by-Line
Which correctly orders the catalytic cycle?
(A)
EP → ES → E + P
(B)
E + S → ES → EP → E + P
(C)
ES → E + S → P
(D)
E + P → EP → ES
Show Answer & NCERT Explanation
Correct Answer: (B) E + S → ES → EP → E + P
E + S → ES → EP → E + P.
Q60 of 70
NEET NCERT Line-by-Line
Malonate's inhibition is relieved by:
(A)
Lowering temperature
(B)
Increasing succinate (substrate) concentration
(C)
Adding more malonate
(D)
Raising pH only
Show Answer & NCERT Explanation
Correct Answer: (B) Increasing succinate (substrate) concentration
Competitive inhibition is overcome by more substrate.
Q61 of 70
NEET NCERT Line-by-Line
Match enzyme class to reaction — which is correct?
(A)
Hydrolases → isomerisation
(B)
Ligases → joining two molecules
(C)
Lyases → hydrolysis
(D)
Transferases → redox
Show Answer & NCERT Explanation
Correct Answer: (B) Ligases → joining two molecules
Ligases join molecules (using ATP).
Q62 of 70
NEET NCERT Line-by-Line
NAD differs from a prosthetic group in that it is:
(A)
A metal ion
(B)
Tightly bound permanently
(C)
A loosely bound coenzyme
(D)
A protein
Show Answer & NCERT Explanation
Correct Answer: (C) A loosely bound coenzyme
Coenzymes like NAD are loosely/transiently bound.
Q63 of 70
NEET NCERT Line-by-Line
Which correctly describes the living state?
(A)
At equilibrium, doing maximum work
(B)
A steady state far from equilibrium that can do work
(C)
A frozen static condition
(D)
Identical to a crystal
Show Answer & NCERT Explanation
Correct Answer: (B) A steady state far from equilibrium that can do work
It is a non-equilibrium steady state.
Q64 of 70
NEET NCERT Line-by-Line
Which is an INCORRECT amino-acid fact?
(A)
Has an amino and carboxyl group
(B)
Glycine R = H
(C)
All proteins are homopolymers
(D)
Exists as a zwitterion
Show Answer & NCERT Explanation
Correct Answer: (C) All proteins are homopolymers
Proteins are heteropolymers, not homopolymers.
Q65 of 70
NEET NCERT Line-by-Line
Carbon makes up about 18.5% of the human body but only ~0.03% of the crust. This shows that:
(A)
Carbon is rare in life
(B)
Life concentrates C relative to the crust
(C)
The crust has no carbon
(D)
Carbon is inorganic only
Show Answer & NCERT Explanation
Correct Answer: (B) Life concentrates C relative to the crust
Living matter is strongly enriched in carbon.
Q66 of 70
NEET NCERT Line-by-Line
Which statement about ribozymes is true?
(A)
They are proteins
(B)
They are RNA molecules acting as enzymes
(C)
They are metal ions
(D)
They are sugars
Show Answer & NCERT Explanation
Correct Answer: (B) They are RNA molecules acting as enzymes
Ribozymes are catalytic RNA molecules.
Q67 of 70
NEET NCERT Line-by-Line
A coenzyme containing niacin and a metal cofactor of carboxypeptidase are, respectively:
(A)
FAD and iron
(B)
NAD and zinc
(C)
Haem and copper
(D)
ATP and magnesium
Show Answer & NCERT Explanation
Correct Answer: (B) NAD and zinc
NAD contains niacin; zinc is carboxypeptidase's cofactor.
Q68 of 70
NEET NCERT Line-by-Line
Which best distinguishes secondary from primary metabolites?
(A)
Secondary ones are always toxic
(B)
Secondary ones often lack a direct physiological role but are humanly useful
(C)
Primary ones are only in plants
(D)
Secondary ones are inorganic
Show Answer & NCERT Explanation
Correct Answer: (B) Secondary ones often lack a direct physiological role but are humanly useful
Secondary metabolites often have no direct role yet are useful (drugs, rubber, pigments).
Q69 of 70
NEET NCERT Line-by-Line
Glycogen and cellulose are both glucose polymers but differ because glycogen is ___ and cellulose is ___.
(A)
structural; storage
(B)
branched storage; unbranched structural
(C)
fructose-based; glucose-based
(D)
an enzyme; a lipid
Show Answer & NCERT Explanation
Correct Answer: (B) branched storage; unbranched structural
Glycogen = branched animal storage; cellulose = unbranched plant structure.
Q70 of 70
NEET NCERT Line-by-Line
Which series is in correct increasing order of structural complexity?
(A)
Quaternary, Tertiary, Secondary, Primary
(B)
Primary, Secondary, Tertiary, Quaternary
(C)
Secondary, Primary, Quaternary, Tertiary
(D)
Tertiary, Quaternary, Primary, Secondary
Show Answer & NCERT Explanation
Correct Answer: (B) Primary, Secondary, Tertiary, Quaternary
Primary → Secondary → Tertiary → Quaternary.