Enzyme introduction mcq 1. Catalyst discovered from biological sources are referred to as ___________ a) vitamins b) carbohydrates c) enzymes d) nucleic acids Answer: c Explanation: Catalyst increase the rate of a chemical reaction without undergoing any change in its structure. In 19th century, catalyst were discovered from biological sources and termed as enzymes. Vitamins, Carbohydrates and Nucleic acids are building blocks of life. 2. All proteins are not enzymes. a) True b) False Answer: a Explanation: Enzymes are basically proteins that perform the function of catalyzing a chemical reaction. But, proteins performs different functions like strength, movement of molecules across membranes, messengers, protect body from the foreign organism, etc. Hence all proteins are not enzymes, but most enzymes are proteins. 3. Enzymes are the polymers of ___________ a) fatty acids b) amino acids c) hexose carbon d) organic phosphate Answer: b Explanation: Enzymes are proteins and proteins are made up of amino acid polymer. Hence enzymes are polymers of amino acids. Fatty acid is the simplest lipid polymer containing long chain of carbon atoms attached to carboxyl group. Organic phosphate is an ester of phosphoric acid. Hexose carbon is a monosaccharide containing 6 carbon atoms. 4. _________ are very efficient catalyst as compared to conventional catalyst. a) Enzymes b) Proteins c) Carbohydrates d) Water Answer: a Explanation: Enzymes are biological catalyst which increases the rate of a particular reaction by a factor of 10 12 or more. As a result, the amount of enzyme required per reaction is less as compared to conventional catalyst. Hence Enzyme is very efficient catalyst. 5. Absolute specificity, group specificity and optical specificity are observed by chemical catalyst. a) True b) False Answer: b Explanation: Absolute specificity, group specificity and optical specificity are observed by enzymes. As enzymes are specific to substrates (Absolute) or group of substrates (Group) or group of substrates showing same optical activity upon hydrolysis. 6. Major drawback of utilizing enzymes is _________ a) high productivity b) specificity c) selectivity d) unstable nature of enzymes Answer: d Explanation: When enzymes are removed from their natural environment, they tend to become unstable making it unfit for use. Hence it’s a major drawback. High productivity, specificity and selectivity are advantages of enzymes. 7. Which of the following is an advantage of enzymes over chemical catalysts? a) High productivity, less material cost b) High cost of enzyme isolation c) High cost of enzyme purification d) Unstable nature of enzymes Answer: a Explanation: Enzymes catalyze a very narrow range of substrate. These enzymes are not selective for a particular reaction, but also has the capacity to differentiate between parts of the same molecule. This leads to the exclusion of any side reactions and removal of byproducts. Thus, providing high productivity and less material cost. 8. ____________ mediates the synthetic and degradative reactions carried out by living organism. a) Cofactor b) Coenzyme c) Enzymes d) Vitamins Answer: c Explanation: Enzymes are biocatalyst which ae obtained from biological sources. They perform the function of catalyzing a particular reaction. Cofactor are mostly metal ions which enzymes during catalysis. Coenzymes are non-protein organic molecule that helps during catalysis. 9. Enzymes work under mild conditions of temperature and pH. a) True b) False Answer: a Explanation: Enzyme work in the range of 5-8 for pH and 20-40° C for temperature. Due to which the problems of undesired reactions which often occur during the traditional method are minimized to a large extent. It also lessens energy requirements, thereby reducing the capital cost which would happen due to corrosion. 10. Enzymes discriminate between similar parts of same molecules. This is termed as __________ a) Stereospecificity b) Absolute specificity c) Regiospecificity d) Group specificity Answer: c Explanation: Regiospecificity means differentiating between parts of same molecule. Absolute specificity means enzymes specific to only one substrate whereas group specificity means enzyme specificity to a group of substrates. Stereospecificity is observed by optical isomers. 11. Trypsin exhibits which kind of specificity? a) Absolute specificity b) Group specificity c) Stereospecificity d) Regiospecificity Answer: b Explanation: Trypsin hydrolyzes most of the proteins along with some peptides and esters. As they catalyze closely related compounds, trypsin exhibits group specificity. 12. What kind of specificity does glucose oxidase exhibit? a) Absolute specificity b) Group specificity c) Stereospecificity d) Regiospecificity Answer: a Explanation: Glucose oxidase oxidizes only one substrate i.e., glucose. When a particular enzyme is exhibiting specificity to only one substrate, it's referred to as absolute specificity. Stereospecificity is exhibited by stereoisomers whereas group specificity means enzyme specificity to a group of substrates. Enzymes have the capacity of discriminating between parts of the same molecule. This kind of specificity is called regiospecificity.
