Zoology MCQs for NEET — Practice Questions with Answers

An apoenzyme is the protein component of an enzyme, which requires a cofactor (non-protein component) to form an active enzyme. Without the cofactor, the apoenzyme is inactive. Therefore, the correct answer is 'Protein'.

A coenzyme is a non-protein compound that binds with an apoenzyme to form an active enzyme. It mainly helps in the transfer of certain chemical groups from one molecule to another. Hence, the correct function of a coenzyme is 'In association with apoenzyme and make it effective'.

Not all enzymes are bidirectional; some enzymes only catalyze reactions in one direction under physiological conditions. Hence, the property 'All enzymes are bidirectional' is not true for enzymes.

The rate of most enzyme-catalyzed reactions reaches a maximum at an optimum pH level. Enzymes have an optimal pH range in which they function most efficiently. Deviations from this pH can result in a decrease in enzyme activity.

Near the freezing point, enzymes are typically inactivated. Low temperatures result in decreased kinetic energy, which reduces the frequency and likelihood of enzyme-substrate collisions, thus reducing enzyme activity.

An enzyme brings about a decrease in the activation energy level of a reaction. By lowering the activation energy, enzymes accelerate the rate of biochemical reactions without being consumed in the process.

Enzymes are large biological molecules (proteins) made up of long chains of amino acids. These amino acids are linked together by peptide bonds to form a polymer. The sequence of amino acids in the enzyme determines its specific shape and function.

Inorganic catalysts, when they attach to an enzyme, often function as activators. Activators are molecules that increase the activity of an enzyme, often by binding to a site on the enzyme and inducing a conformational change that enhances its activity.

The substrate combines with the enzyme at the active site. The active site is a specific region on the enzyme where the substrate binds and undergoes a chemical reaction. The shape and chemical environment of the active site are complementary to the substrate, allowing for a high degree of specificity.

The correct answer is 'E-S complex.' The interaction between an enzyme (E) and a substrate (S) forms an enzyme-substrate complex (E-S complex). This is a temporary molecular structure formed when an enzyme comes into perfect contact with its substrate. This complex formation is crucial for the catalytic activity of enzymes, as it allows the enzyme to perform its function of converting substrates into products.