Free Macromolecules MCQs with Answers

• A. a glycosidic linkage
• B. a peptide linkage, formed by condensation between a carboxyl and an amino group
• C. an ester linkage
• D. a hydrogen bond

Explanation: The carboxyl group of one amino acid condenses with the amino group of the next, releasing water and leaving a CO-NH amide link known as…

• A. dissolves only in organic solvents
• B. contains a benzene ring
• C. contains both an acidic carboxyl group and a basic amino group, so it reacts with both acids and bases
• D. has no charge under any conditions

Explanation: The carboxyl group can donate a proton and the amino group can accept one, so an amino acid neutralises both acids and alkalis.

• A. neutral point
• B. isoelectric point
• C. equivalence point
• D. melting point

Explanation: At the isoelectric point the positive and negative charges within the molecule exactly balance, so the net charge is zero and the amino…

• A. insoluble in water and structural in function
• B. soluble in water and catalytic in function
• C. always an enzyme
• D. made of a single amino acid repeated

Explanation: Fibrous proteins consist of long parallel chains held in bundles, which makes them tough, insoluble and suited to structural roles in…

• A. peptide bonds between amino acids
• B. ionic bonds between side chains only
• C. hydrogen bonds between the carbonyl and amide groups of the backbone
• D. disulphide bridges only

Explanation: Regular coiling or pleating arises because each carbonyl oxygen hydrogen bonds to an amide hydrogen further along the same chain, giving…

• A. hydrolysis of all its peptide bonds
• B. loss of its three dimensional shape while the amino acid sequence remains intact
• C. a change in its amino acid sequence
• D. conversion of the protein into a carbohydrate

Explanation: Heat, extreme pH, heavy metal ions and alcohol break the weak interactions holding the fold, so the chain unravels and biological activity…

• A. glucose molecules
• B. fatty acids and glycerol
• C. a mixture of amino acids
• D. urea and ammonia

Explanation: Every peptide bond is broken by boiling with concentrated acid or by protease enzymes, releasing the constituent amino acids, which can…

• A. Acting as enzymes
• B. Transporting oxygen
• C. Providing antibodies for defence
• D. Serving as the main long term energy store

Explanation: The body stores energy as fat and, in the short term, as glycogen, and proteins are broken down for energy only when those stores are…

• A. a violet colour with copper two ions in alkaline solution
• B. a brick red precipitate
• C. a silver mirror
• D. a blue black colour

Explanation: Copper two ions form a violet complex with the peptide linkages, so the test detects the presence of peptide bonds rather than any…

• A. are used up in the reactions they catalyse
• B. raise the activation energy of a reaction
• C. supply energy to drive unfavourable reactions
• D. speed up reactions by lowering the activation energy and are recovered unchanged

Explanation: An enzyme provides an alternative pathway with a smaller energy barrier, so a far larger proportion of collisions are effective at body…

• A. the shape and chemistry of its active site
• B. its molar mass
• C. the temperature of the reaction
• D. the concentration of the substrate

Explanation: Only a substrate whose shape and charge distribution complement the active site can bind, which is why sucrase acts on sucrose but not on…

• A. the substrate evaporates
• B. the enzyme is denatured as the weak bonds holding its tertiary structure break
• C. the enzyme is used up faster
• D. the activation energy increases

Explanation: Heat disrupts the hydrogen and ionic interactions that hold the chain in shape, so the active site loses its precise geometry and can no…

• A. denaturing the enzyme permanently
• B. binding an allosteric site
• C. occupying the active site because it resembles the substrate
• D. lowering the temperature

Explanation: Substrate and inhibitor compete for the same site, so the inhibition can be overcome by increasing the substrate concentration and the…

• A. Protein and glucose
• B. Starch and amino acid
• C. Nucleic acid and fatty acid
• D. Protein and amino acid

Explanation: Proteins are polymers of amino acids, starch and cellulose of glucose, and nucleic acids of nucleotides, while fats are not true polymers…

• A. contains a disulphide bridge
• B. is fibrous
• C. consists of two or more polypeptide chains associated together
• D. contains more than one hundred amino acids

Explanation: Quaternary structure describes how separate polypeptide subunits fit together, as in haemoglobin with its two alpha and two beta chains…

• A. only amino acids
• B. a non protein prosthetic group in addition to the polypeptide
• C. no peptide bonds
• D. two identical chains

Explanation: A conjugated protein is bound to a non protein group, so haemoglobin carries a haem group, glycoproteins carry carbohydrate and…

• A. increase enzyme activity uncontrollably
• B. are converted into proteins by the body
• C. supply too much energy to the cell
• D. bind to sulphur containing groups in enzymes and denature them irreversibly

Explanation: These ions attack the sulphydryl side chains of cysteine, breaking disulphide bridges and destroying the tertiary structure, so the…

• A. alters the charges on the side chains, changing the shape of the active site
• B. changes the molar mass of the enzyme
• C. removes the substrate from the solution
• D. converts the enzyme into a carbohydrate

Explanation: Excess hydrogen or hydroxide ions interfere with the ionic and hydrogen bonds between side chains, distorting the active site so the…

• A. the fastest source of energy
• B. amino acids for the growth and repair of tissues
• C. essential fatty acids
• D. dietary fibre

Explanation: Digested protein provides the amino acids the body reassembles into its own enzymes, hormones, antibodies and structural tissue, and this…

• A. the sequence of amino acids joined by peptide bonds
• B. the coiling of the chain into a helix
• C. the folding of the chain into a globular shape
• D. the association of several chains

Explanation: Primary structure is simply the order of the residues, and it determines every higher level of structure, because the chain folds…