Biology · Cell: Structure and Function · Practice set
Biomolecules Practice Set · 20 MCQs with Solutions
Twenty exam-style Biomolecules questions across every part of the chapter, each with a worked explanation and a balanced answer key. Free to read or download.
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Biomolecules is tested as recall with a twist, so practice matters more than re-reading. These twenty questions cover every part of the chapter, from the acid-soluble pool to enzyme kinetics, and each answer explains not just which option is right but why the tempting one is wrong.
Q
20 Practice Questions
Single correct answer. Attempt all 20 before checking the key. Covers carbohydrates, proteins, enzymes, vitamins and nucleic acids.
Q1Carbohydrates
Which of the following is a non-reducing sugar?
AMaltose
BLactose
CGlucose
DSucrose
Q2Carbohydrates
The bond that joins two monosaccharide units in a disaccharide is a:
APhosphodiester bond
BGlycosidic bond
CHydrogen bond
DPeptide bond
Q3Carbohydrates
The most abundant carbohydrate in nature is:
AGlucose
BGlycogen
CCellulose
DStarch
Q4Proteins
The linkage present in proteins is the:
AGlycosidic bond
BPhosphodiester bond
CEster bond
DPeptide bond
Q5Proteins
The secondary structure of a protein (α-helix and β-sheet) is stabilised mainly by:
ADisulphide bridges
BIonic bonds
CHydrogen bonds
DPeptide bonds
Q6Proteins
On denaturation of a protein, which level of structure remains intact?
ASecondary
BPrimary
CQuaternary
DTertiary
Q7Proteins
The number of amino acids commonly found in proteins is:
A16
B20
C64
D4
Q8Vitamins
Which vitamin deficiency causes scurvy?
AVitamin D
BVitamin K
CVitamin C
DVitamin A
Q9Vitamins
Which set contains only fat-soluble vitamins?
AA, D, E, K
BC, D, E, K
CB, C, D, K
DA, B, C, D
Q10Vitamins
The chemical name of vitamin B1 is:
ARiboflavin
BThiamine
CAscorbic acid
DRetinol
Q11Nucleic Acids
A nucleoside consists of:
ABase + sugar
BSugar + phosphate
CBase + sugar + phosphate
DBase + phosphate
Q12Nucleic Acids
Which of the following is a purine base?
AThymine
BAdenine
CUracil
DCytosine
Q13Nucleic Acids
In DNA, adenine pairs with thymine through how many hydrogen bonds?
AFour
BThree
CTwo
DOne
Q14Nucleic Acids
The sugar present in RNA is:
AFructose
BGlucose
C2-deoxyribose
DRibose
Q15Enzymes
Enzymes are chemically:
AMostly carbohydrates
BMostly lipids
CMostly proteins
DAlways nucleic acids
Q16Enzymes
The non-protein part of an enzyme that is tightly and permanently bound is called a:
AProsthetic group
BHoloenzyme
CApoenzyme
DCoenzyme
Q17Enzymes
Enzymes accelerate reactions by:
ALowering the activation energy
BRaising the activation energy
CChanging the equilibrium constant
DIncreasing the temperature
Q18Carbohydrates
Which storage carbohydrate is found in animals?
AInulin
BCellulose
CStarch
DGlycogen
Q19Proteins
The most abundant protein in the animal world is:
AHaemoglobin
BInsulin
CKeratin
DCollagen
Q20Carbohydrates
Which of the following is NOT a polysaccharide?
ASucrose
BGlycogen
CStarch
DCellulose
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Answer Key & Solutions
Q1D
Q2B
Q3C
Q4D
Q5C
Q6B
Q7B
Q8C
Q9A
Q10B
Q11A
Q12B
Q13C
Q14D
Q15C
Q16A
Q17A
Q18D
Q19D
Q20A
Q1Correct: DSucrose
Sucrose is non-reducing because both anomeric carbons (of glucose and fructose) are tied up in the glycosidic bond, leaving no free aldehyde or ketone group. Maltose, lactose and glucose all have a free reducing group.
Q2Correct: BGlycosidic bond
A glycosidic bond is the oxygen bridge linking two sugar units, formed with loss of water. Peptide bonds join amino acids, phosphodiester bonds join nucleotides, and hydrogen bonds hold DNA strands together.
Q3Correct: CCellulose
Cellulose, the structural polysaccharide of plant cell walls (made of β-glucose), is the most abundant carbohydrate and organic polymer on Earth.
Q4Correct: DPeptide bond
Proteins are polymers of amino acids joined by peptide bonds (−CO−NH−), formed by condensation of a carboxyl and an amino group.
Q5Correct: CHydrogen bonds
Secondary structure is held by hydrogen bonds between backbone groups. Peptide bonds define the primary structure; disulphide and ionic bonds contribute more to tertiary structure.
Q6Correct: BPrimary
Denaturation destroys the secondary, tertiary and quaternary structure (breaking non-covalent bonds), but the primary structure, held by covalent peptide bonds, is preserved.
Q7Correct: B20
There are 20 standard amino acids. The number 64 is the count of codons, and 4 is the number of DNA bases.
Q8Correct: CVitamin C
Scurvy results from a deficiency of vitamin C (ascorbic acid). Vitamin A deficiency causes night blindness, D causes rickets, and K causes poor blood clotting.
Q9Correct: AA, D, E, K
The fat-soluble vitamins are A, D, E and K; they are stored in the body. The B-complex and C are water-soluble and excreted in urine.
Q10Correct: BThiamine
Vitamin B1 is thiamine (its deficiency causes beriberi). Retinol is vitamin A, riboflavin is B2, and ascorbic acid is vitamin C.
Q11Correct: ABase + sugar
A nucleoside is a nitrogenous base joined to a pentose sugar. Adding a phosphate group converts it to a nucleotide.
Q12Correct: BAdenine
Adenine and guanine are purines (double-ring). Cytosine, thymine and uracil are pyrimidines (single-ring).
Q13Correct: CTwo
A-T pairs form two hydrogen bonds, while G-C pairs form three. This is why GC-rich DNA is more thermally stable.
Q14Correct: DRibose
RNA contains ribose; DNA contains 2-deoxyribose (one oxygen fewer at the 2' carbon).
Q15Correct: CMostly proteins
Almost all enzymes are globular proteins. The exception is ribozymes, which are catalytic RNA molecules.
Q16Correct: AProsthetic group
A prosthetic group is a tightly (permanently) bound cofactor. A coenzyme is loosely bound; the apoenzyme is the protein part alone; the holoenzyme is the complete active enzyme.
Q17Correct: ALowering the activation energy
Enzymes lower the activation energy, so more molecules can react per unit time. They do not shift the equilibrium position, only the rate at which it is reached.
Q18Correct: DGlycogen
Glycogen is the animal storage carbohydrate. Starch stores energy in plants, cellulose is structural, and inulin is a fructose polymer.
Q19Correct: DCollagen
Collagen, the main structural protein of connective tissue, is the most abundant protein in animals. RuBisCO is the most abundant protein on Earth overall.
Q20Correct: ASucrose
Sucrose is a disaccharide (glucose + fructose). Starch, cellulose and glycogen are all polysaccharides.
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Quick Revision
Everything for revision day.SCORE
20 questions
1 mark each
check key after
TIP
reducing sugar = free CHO
sucrose non-reducing
denature: 1° survives
REVISE
A=T (2H), G=C (3H)
fat-sol: A D E K
enzymes lower Ea
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