Answer the question on the basis of passage given below:
Adsorption is the phenomenon of attracting and retaining the molecules of a substance on the surface of a solid resulting into a higher concentration on the surface than in the bulk. The variation in the amount of gas adsorbed by the adsorbent with pressure at constant temperature is expressed as isotherm. A catalyst is a substance, when adsorbed enhances the rate of a chemical reaction without itself getting used up in the reaction. Depending on the type of the particles of the dispersed phase, colloids are classified as multimolecular, macromolecular and associated colloids and soap is such an example of associated colloids. Colloids show various properties such as Tyndall effect, colour, Brownian movement and charge development. There are positively charged sols and negatively charged sols. Due to this, electrophoresis and electroosmosis are shown by colloids.
Enzyme catalysts
A. are highly efficient.
B. decrease their activity in the presence of co-enzymes.
C. are highly active under optimum pH.
D. are not specific in nature.
E. does not work in the presence of inhibitors.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A, C and E only
Enzymes are protein molecules that act as biological catalysts. They are remarkably efficient and highly specific, they work best at an optimum temperature and an optimum pH, their activity is raised by activators and co-enzymes, and they are inhibited or poisoned by certain substances.
(A) are highly efficient. — Correct. One enzyme molecule can transform about a million molecules of reactant per minute.
(B) decrease their activity in the presence of co-enzymes. — Incorrect. Co-enzymes (small non-protein molecules such as vitamins) and activators increase enzyme activity.
(C) are highly active under optimum pH. — Correct. The rate of an enzyme-catalysed reaction is highest at a particular pH, the optimum pH, usually between 5 and 7.
(D) are not specific in nature. — Incorrect. Enzymes are highly specific; urease, for example, catalyses only the hydrolysis of urea.
(E) does not work in the presence of inhibitors. — Correct. Inhibitors and poisons bind to the active groups of the enzyme and reduce or destroy its catalytic activity.
NCERT (Pre-rationalised edition, 2022-23):
Characteristics of Enzyme Catalysis – “Enzyme catalysis is unique in its efficiency and high degree of specificity. The following characteristics are exhibited by enzyme catalysts: (i) Most highly efficient: One molecule of an enzyme may transform one million molecules of the reactant per minute. (ii) Highly specific nature: Each enzyme is specific for a given reaction, i.e., one catalyst cannot catalyse more than one reaction. For example, the enzyme urease catalyses the hydrolysis of urea only. It does not catalyse hydrolysis of any other amide. … (iv) Highly active under optimum pH: The rate of an enzyme-catalysed reaction is maximum at a particular pH called optimum pH, which is between pH values 5-7. … (v) Increasing activity in presence of activators and co-enzymes: The enzymatic activity is increased in the presence of certain substances, known as co-enzymes. … (vi) Influence of inhibitors and poisons: Like ordinary catalysts, enzymes are also inhibited or poisoned by the presence of certain substances. The inhibitors or poisons interact with the active functional groups on the enzyme surface and often reduce or completely destroy the catalytic activity of the enzymes.”