Biomolecules NEET PYQReal NEET & AIPMT 2005–2021 questions, year-tagged, with solutions
By the RankUp team, founded by Dr. Deepak Sahu (MBBS Gold Medalist, NEET PG AIR 1731) · Updated
Every Biomolecules question from the NEET & AIPMT papers on this site (2005–2021), newest first. Each is tagged with its paper. Tap an option to check your answer and read the explanation.
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Biomolecules previous year questions
41 questions. Tap an option to check your answer.
Q1NEET 2021
Which of the following are not secondary metabolites in plants ?
Not quite — the answer is B.
Amino acids and glucose are primary metabolites used in basic metabolism like respiration and protein synthesis. Morphine and codeine (alkaloids), vinblastin and curcumin (drugs) and rubber and gums are secondary metabolites.
Q2NEET 2021
Match List - I with List - II. List - I | List - II (a) Protein | (i) C = C double bonds (b) Unsaturated fatty acid | (ii) Phosphodiester bonds (c) Nucleic acid | (iii) Glycosidic bonds (d) Polysaccharide | (iv) Peptide bonds Choose the correct answer from the options given below.
Not quite — the answer is A.
Amino acids in proteins are linked by peptide bonds, unsaturated fatty acids have C = C double bonds, nucleotides in nucleic acids are joined by phosphodiester bonds, and sugars in polysaccharides by glycosidic bonds. Hence (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii).
Q3NEET 2021
Identify the incorrect pair.
Not quite — the answer is D.
Ricin, like abrin, is a toxin, so pairing it with drugs is incorrect. Codeine is an alkaloid, abrin a toxin and concanavalin A a lectin, so those pairs are correct.
Q4NEET 2021
Following are the statements with reference to 'lipids'. (a) Lipids having only single bonds are called unsaturated fatty acids. (b) Lecithin is a phospholipid. (c) Trihydroxy propane is glycerol. (d) Palmitic acid has 20 carbon atoms including carboxyl carbon. (e) Arachidonic acid has 16 carbon atoms. Choose the correct answer from the options given below.
Not quite — the answer is C.
Lecithin is a phospholipid and glycerol is trihydroxy propane, so (b) and (c) are true. Fatty acids with only single bonds are saturated, palmitic acid has 16 carbons and arachidonic acid has 20, so (a), (d) and (e) are false.
Q5NEET 2020 · Q11
Identify the substances having glycosidic bond and peptide bond, respectively in their structure:
Not quite — the answer is D.
Inulin is a polymer of fructose units linked by glycosidic bonds, and insulin is a protein whose amino acids are linked by peptide bonds. Cholesterol is a steroid with neither bond, glycerol is a simple alcohol, and lecithin is a phospholipid, so the other pairs fail.
Q6NEET 2020 · Q30
Match the following: (a) Inhibitor of catalytic activity | (i) Ricin (b) Possess peptide bonds | (ii) Malonate (c) Cell wall material in fungi | (iii) Chitin (d) Secondary metabolite | (iv) Collagen Choose the correct option from the following:
Not quite — the answer is A.
Malonate is a competitive inhibitor of succinate dehydrogenase, collagen is a protein with peptide bonds, chitin is the fungal cell-wall material, and ricin is a toxin listed as a secondary metabolite. Hence malonate, collagen, chitin, ricin is correct.
Q7NEET 2020 · Q41
Secondary metabolites such as nicotine, strychnine and caffeine are produced by plants for their:
Not quite — the answer is C.
Alkaloids such as nicotine, strychnine and caffeine are secondary metabolites that protect plants by making them toxic or unpalatable to herbivores. They have no nutritive role and are not growth or reproductive substances.
Q8NEET 2020 · Q79
Identify the basic amino acid from the following.
Not quite — the answer is C.
Lysine has an extra amino group in its R group, making it a basic amino acid. Glutamic acid is acidic, while tyrosine (aromatic) and valine are neutral.
Q9NEET 2020 · Q82
Which one of the following is the most abundant protein in the animals?
Not quite — the answer is B.
Collagen is the most abundant protein in the animal world. RuBisCO is the most abundant protein in the whole biosphere, and haemoglobin, lectin and insulin are present in far smaller amounts.
Q10NEET 2019 · Q112
Concanavalin A is :
Not quite — the answer is C.
Concanavalin A is a lectin, a carbohydrate-binding protein from jack bean, listed among secondary metabolites. Alkaloids such as morphine and essential oils such as lemongrass oil are different classes.
Q11NEET 2018 · Q117
The two functional groups characteristic of sugars are
Not quite — the answer is D.
Sugars are polyhydroxy aldehydes or ketones, so they carry several hydroxyl groups and one carbonyl group (aldehyde or keto). Phosphate occurs only in sugar phosphates and nucleotides, and a methyl group is not characteristic of sugars.
Q12NEET 2017 · Q54
Which of the following are not polymeric?
Not quite — the answer is D.
Lipids are small molecules (molecular weight below about 800 Da) built from fatty acids and glycerol, not repeating monomers, so they are not true polymers; they only appear in the acid-insoluble fraction because they form membrane vesicles. Nucleic acids, proteins and polysaccharides are polymers of nucleotides, amino acids and monosaccharides.
Q13NEET 2017 (Gujarati paper) · Q52
Which of the following statements regarding enzyme inhibition is correct?
Not quite — the answer is B.
In competitive inhibition a substrate-like inhibitor and the substrate compete for the same active site. It is competitive (not non-competitive) inhibition that can be overcome by raising substrate concentration, and non-competitive inhibitors typically bind reversibly at an allosteric site.
Q14NEET 2017 (Gujarati paper) · Q57
A fat molecule is formed from:
Not quite — the answer is C.
A fat (triglyceride) is formed by esterification of the three hydroxyl groups of one glycerol with three fatty acids. One glycerol with one fatty acid gives only a monoglyceride.
Q15NEET 2017 (Gujarati paper) · Q127
Which of the following enzymes is not protein?
Not quite — the answer is D.
Ribozymes are catalytic RNA molecules (for example the peptidyl transferase activity of rRNA), so they are not proteins. Polymerases, ligases and lysozyme are all protein enzymes.
Q16NEET 2016 Phase 2 · Q103
A non-proteinaceous enzyme is
Not quite — the answer is B.
A ribozyme is an RNA molecule with catalytic activity, such as the 23S rRNA that acts as peptidyl transferase, so it is not a protein. Lysozyme, ligase and deoxyribonuclease are all protein enzymes.
Q17NEET 2016 Phase 2 · Q143
Which of the following is the least likely to be involved in stabilizing the three-dimensional folding of most proteins?
Not quite — the answer is D.
The tertiary structure of proteins is held by hydrogen bonds, ionic (electrostatic) interactions, hydrophobic interactions and disulphide bridges. Ester bonds join fatty acids to glycerol in lipids and are not used to hold protein folds.
Q18NEET 2016 Phase 1 · Q153
Which one of the following statements is wrong?
Not quite — the answer is D.
Glycine is the simplest amino acid with H as its side chain and has no sulphur; the sulphur-containing amino acids are cysteine and methionine. The other statements are correct.
Q19NEET 2016 Phase 1 · Q180
A typical fat molecule is made up of:
Not quite — the answer is B.
A typical fat (triglyceride) is formed by esterification of one glycerol molecule with three fatty acid molecules. Monoglycerides have only one fatty acid, and fats never contain three glycerols.
Q20AIPMT 2015
Which one of the following statements is incorrect?
Not quite — the answer is A.
A competitive inhibitor competes with the substrate for the active site, so more substrate is needed to reach half Vmax, i.e. the apparent Km increases, not decreases. It binds reversibly and is not chemically changed by the enzyme.
Q21AIPMT 2014
Select the option which is not correct with respect to enzyme action:
Not quite — the answer is A.
Malonate resembles succinate and is a competitive inhibitor of succinic dehydrogenase, so adding a large excess of succinate out-competes it and reverses the inhibition; the statement that it does not reverse the inhibition is therefore incorrect. The other statements (substrate binds at the active site, non-competitive inhibitors bind elsewhere, malonate is competitive) are all true.
Q22AIPMT 2014
Which one of the following is a non-reducing carbohydrate?
Not quite — the answer is A.
In sucrose the glycosidic bond joins C1 of glucose with C2 of fructose, so both reducing (carbonyl) groups are tied up and the sugar is non-reducing. Lactose and maltose each keep one free anomeric carbon and ribose 5-phosphate has a free aldehyde group, so they are reducing.
Q23NEET 2013
Transition state structure of the substrate formed during an enzymatic reaction is
Not quite — the answer is C.
The transition state of the substrate exists only very briefly at the top of the energy barrier and is a high-energy, unstable structure before it forms product. It is therefore both transient and unstable, not stable or permanent.
Q24NEET 2013
A phosphoglyceride is always made up of
Not quite — the answer is C.
In a phosphoglyceride (e.g. lecithin), fatty acids, which may be saturated or unsaturated, are esterified to glycerol, and the glycerol also carries a phosphate group. The fatty acid is not esterified to the phosphate, and it need not be only saturated or only unsaturated.
Q25NEET 2013
The most abundant intracellular cation is
Not quite — the answer is D.
Potassium ion is the chief cation inside cells, while sodium ion is the chief cation of extracellular fluid. Calcium and hydrogen ions are present inside cells at far lower concentrations.
Q26NEET 2013
Macromolecule chitin is
Not quite — the answer is A.
Chitin is a homopolymer of N-acetylglucosamine, so it is a nitrogen-containing polysaccharide. It is a complex polysaccharide with amino sugar units, not a simple one, and it has no phosphorus or sulphur.
Q27NEET 2013
The essential chemical components of many coenzymes are
Not quite — the answer is D.
Many coenzymes are derived from vitamins, e.g. NAD and NADP contain niacin and FAD contains riboflavin. Coenzymes are non-protein organic compounds, so proteins are not their components.
Q28AIPMT 2012 Mains
For its activity, carboxypeptidase requires
Not quite — the answer is A.
Carboxypeptidase is a metalloenzyme that needs zinc as its cofactor. Niacin is a vitamin forming the coenzymes NAD/NADP, not the cofactor of this enzyme.
Q29AIPMT 2012 Mains
Which one of the following biomolecules is correctly characterised ?
Not quite — the answer is A.
Lecithin is a phospholipid, a glyceride carrying a phosphate group, and it is a major part of cell membranes. Palmitic acid is a saturated 16-carbon fatty acid, and adenylic acid contains ribose, not glucose.
Q30AIPMT 2012 Prelims
Which one of the structures given below correctly represents the structural formula of the basic amino acid?
Not quite — the answer is B.
Lysine, H₂N–CH(COOH)–(CH₂)₄–NH₂, carries an extra amino group in its side chain, which makes it a basic amino acid. The structure with an extra –COOH in the side chain is glutamic acid (acidic), the one with –CH₂OH is serine (neutral), and HOCH₂–CH₂–CH₂–NH₂ is not an amino acid at all.
Q31AIPMT 2012 Prelims
Which one is the most abundant protein in the animal world ?
Not quite — the answer is D.
Collagen is the most abundant protein in the animal world. RuBisCO is the most abundant protein in the whole biosphere, but it is a plant protein; haemoglobin, insulin and trypsin are far less abundant.
Q32AIPMT 2010 Mains · Q43
Three of the following statements about enzymes are correct and one is wrong. Which one is wrong?
Not quite — the answer is D.
Almost all enzymes are proteins, and the non-protein exceptions are RNA molecules (ribozymes), not lipids. Enzymes of thermophilic organisms in hot springs do stay active at 80-90°C, and enzymes do have an optimum pH and high specificity.
Q33AIPMT 2008 Prelims · Q112
A competitive inhibitor of succinic dehydrogenase is
Not quite — the answer is B.
Malonate closely resembles succinate in structure, so it binds the active site of succinic dehydrogenase and competes with the substrate, the NCERT example of competitive inhibition. Malate and oxaloacetate are downstream Krebs cycle intermediates, not the classic inhibitor.
Q34AIPMT 2008 Prelims · Q114
Carbohydrates are commonly found as starch in plant storage organs. Which of the following five properties of starch (a - e) make it useful as a storage material? a. Easily translocated b. Chemically non-reactive c. Easily digested by animals d. Osmotically inactive e. Synthesized during photosynthesis The useful properties are
Not quite — the answer is C.
Starch is a large, insoluble polymer, so it is chemically unreactive and exerts no osmotic effect, letting cells store a lot of it without drawing in water. It is not easily translocated (sugars like sucrose are), and being digestible by animals is irrelevant to the plant's storage needs.
Q35AIPMT 2007 Prelims · Q136
About 98 percent of the mass of every living organism is composed of just six elements including carbon, hydrogen, nitrogen, oxygen and
Not quite — the answer is C.
Oxygen, carbon, hydrogen, nitrogen, calcium and phosphorus together make up about 98-99% of body mass; calcium and phosphorus are abundant in bone and nucleic acids. Sulphur, sodium and magnesium are present only in much smaller amounts.
Q36AIPMT 2006 Prelims · Q137
An organic substance bound to an enzyme and essential for its activity is called :
Not quite — the answer is A.
An organic non-protein molecule that binds an enzyme and is needed for its activity is a coenzyme (a tightly bound one is called a prosthetic group). An apoenzyme is the protein part alone, and a holoenzyme is the complete active enzyme.
Q37AIPMT 2005 Prelims · Q133
Nucleotide are building blocks of nucleic acids, nucleotide is a composite molecule formed by :
Not quite — the answer is C.
A nucleotide is a nitrogenous base joined to a pentose sugar (a nucleoside) plus a phosphate group. '(base-sugar-phosphate)n' describes a polynucleotide chain, and 'base-sugar' alone is a nucleoside.
Q38AIPMT 2005 Prelims · Q137
Which of the following is the simplest amino acid ?
Not quite — the answer is C.
Glycine is the simplest amino acid because its R group is just a hydrogen atom. Alanine has a methyl group, and tyrosine and asparagine have larger side chains.
Q39AIPMT 2005 Prelims · Q140
Enzymes, vitamins and hormones can be classified into a single category of biological chemicals, because all of these :
Not quite — the answer is D.
What enzymes, vitamins (often as coenzymes) and hormones have in common is that they control the rate and direction of metabolism. They are not all proteins (many vitamins and steroid hormones are not), and vitamins are mostly obtained from food rather than made in the body.
Q40AIPMT 2005 Prelims · Q179
Which of the following statements regarding enzyme inhibition is correct ?
Not quite — the answer is C.
In competitive inhibition, a substrate-like inhibitor competes with the substrate for the enzyme's active site (for example malonate against succinate). Adding more substrate overcomes competitive inhibition, not non-competitive inhibition.
Q41AIPMT 2005 Prelims · Q181
The catalytic efficiency of two different enzymes can be compared by the :
Not quite — the answer is A.
Km, the substrate concentration that gives half the maximum velocity, reflects an enzyme's affinity for its substrate: a lower Km means higher affinity and efficiency. It is the standard value for comparing enzymes. pH optimum and molecular size say nothing about catalytic efficiency.
How often Biomolecules came up
Questions from this chapter in each paper on this site.
- NEET 2021: 4
- NEET 2020: 5
- NEET 2019: 1
- NEET 2018: 1
- NEET 2017: 1
- NEET 2017 (Gujarati paper): 3
- NEET 2016 Phase 2: 2
- NEET 2016 Phase 1: 2
- AIPMT 2015: 1
- AIPMT 2014: 2
- NEET 2013: 5
- AIPMT 2012 Mains: 2
- AIPMT 2012 Prelims: 2
- AIPMT 2010 Mains: 1
- AIPMT 2008 Prelims: 2
- AIPMT 2007 Prelims: 1
- AIPMT 2006 Prelims: 1
- AIPMT 2005 Prelims: 5
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