Free Macromolecules MCQs with Answers

• A. peptide bonds along the backbone
• B. hydrogen bonds between backbone carbonyl and amide groups
• C. disulphide bridges between cysteines
• D. ionic bonds between side chains

Explanation: Regular hydrogen bonding between a carbonyl oxygen and an amide hydrogen four residues further along coils the chain into a helix.

• A. cysteine residues
• B. glycine residues
• C. lysine residues
• D. serine residues

Explanation: Two sulphydryl groups are oxidised to form a covalent S-S link, the strongest of the interactions holding tertiary structure.

• A. collagen
• B. haemoglobin
• C. insulin
• D. keratin

Explanation: Haemoglobin is a globular conjugated protein of four chains, each holding an iron containing haem group that binds one oxygen molecule…

• A. soluble in water and act as enzymes
• B. insoluble in water and serve structural roles
• C. always conjugated
• D. made of a single amino acid

Explanation: Long parallel chains bundled together make fibrous proteins tough and insoluble, which suits keratin in hair, collagen in tendons and…

• A. carbon dioxide
• B. a molecule of water
• C. ammonia
• D. hydrogen

Explanation: Condensation between the carboxyl group of one residue and the amino group of the next expels water and creates the peptide link.

• A. raising the temperature of the substrate
• B. binding the substrate at its active site and stabilising the transition state
• C. supplying energy to the reactants
• D. changing the equilibrium position

Explanation: Binding orients the substrate correctly and strains the bonds that are about to break, offering a lower energy route to the products.

• A. far less efficient
• B. highly specific and effective at mild temperature and pH
• C. unaffected by temperature
• D. consumed during the reaction

Explanation: Enzymes achieve rate enhancements that industrial catalysts cannot approach and do so at body temperature and near neutral pH, but they…

• A. how many substrate molecules one enzyme molecule converts per unit time
• B. the number of enzymes in a cell
• C. the temperature at which it denatures
• D. its molar mass

Explanation: Carbonic anhydrase converts around 600,000 molecules of carbon dioxide per second, which is why the reaction in red blood cells is…

• A. It occupies most of the enzyme's surface
• B. It is a small region whose shape and charges complement the substrate
• C. It binds any molecule of similar mass
• D. It is destroyed after each reaction

Explanation: Only a few residues, often far apart in the primary sequence but brought together by folding, form the active site, which is why the whole…

• A. amylase
• B. rennin
• C. lipase
• D. pepsin

Explanation: Rennin, also called chymosin, clots the milk protein casein, which is the first step in cheese production and is also present in the…

• A. large molecules built from repeating amino acid units
• B. made of two identical halves
• C. always branched
• D. insoluble in all solvents

Explanation: A polymer is any large molecule assembled from many small repeating units, and in a protein those units are amino acids joined by peptide…

• A. 4
• B. 20
• C. 64
• D. 100

Explanation: Twenty amino acids account for almost all natural protein, and their enormous number of possible sequences is what allows such variety of…

• A. no charged groups
• B. a positive charge on the amino group and a negative charge on the carboxyl group at the same time
• C. two positive charges
• D. a single negative charge only

Explanation: The carboxyl group donates its proton to the amino group within the same molecule, so the ion has both charges and a net charge of zero at…

• A. Boiling
• B. Strong acid
• C. Heavy metal ions
• D. Dissolving it in pure water at room temperature

Explanation: Many proteins dissolve in water without any loss of structure, since water is the medium they normally function in.

• A. raise blood glucose concentration
• B. lower blood glucose concentration by promoting uptake and storage
• C. digest proteins in the stomach
• D. carry oxygen

Explanation: Secreted by the beta cells of the pancreas, insulin increases the permeability of cells to glucose and stimulates its conversion into…

• A. catalysing reactions
• B. providing tensile strength in skin, tendon and bone
• C. transporting oxygen
• D. storing genetic information

Explanation: Its triple helix of three chains wound together gives collagen enormous tensile strength, which is why tendons and ligaments resist…

• A. the substrate begins to inhibit the enzyme
• B. all the active sites are occupied, so the enzyme is saturated
• C. the enzyme is denatured by the substrate
• D. the products stop the reaction

Explanation: Once every active site is engaged, adding more substrate cannot increase the rate, and the plateau reached is Vmax.

• A. an inorganic metal ion
• B. an organic molecule, often derived from a vitamin
• C. part of the polypeptide chain
• D. a type of substrate

Explanation: NAD, FAD and coenzyme A are organic helpers built from niacin, riboflavin and pantothenic acid respectively, whereas cofactors such as…

• A. albumin
• B. haemoglobin
• C. keratin
• D. fibroin

Explanation: Haemoglobin carries a non protein haem prosthetic group that does the actual oxygen binding, which makes it conjugated.

• A. Amylase
• B. Protease
• C. Lipase
• D. Urease

Explanation: Pancreatic lipase hydrolyses triglycerides into fatty acids and glycerol in the duodenum, working on the enormous surface created after…