1. The sum of all chemical reactions going on in a cell is called:
Answer: B. metabolism
Biology Class 11 Unit 3: Enzymes MCQs
146 multiple choice questions with the correct answer for each. Tap an option to check yourself, or switch on "Show all answers". This is page 1 of 3.
Tap an option to check your answer.
2. Enzymes are defined as:
Answer: B. biological polymers that catalyse biochemical reactions
3. The name "diastase" was given by Payen and Persoz to the substance that:
Answer: C. digested starch in ground barley
4. Enzymes exist in the cell as:
Answer: C. colloids
5. All enzymes are:
Answer: B. globular proteins made up of one or more polypeptides (except ribozymes)
6. Ribozymes are enzymes made up of:
Answer: B. RNA
7. An example of a ribozyme which forms peptide bonds during protein synthesis is:
Answer: B. peptidyl transferase
8. The catalytic activity of an enzyme is located in its:
Answer: B. active site
9. The active site of an enzyme is a:
Answer: B. specific charge-bearing three-dimensional cavity
10. The substrate is attached to the active site by:
Answer: C. non-covalent interactions such as hydrogen bonds and hydrophobic interactions
11. An active site usually consists of how many amino acids?
Answer: B. 3 to 12
12. The two functional regions of an active site are the:
Answer: B. binding site and catalytic site
13. The part of the active site that converts substrate into product is the:
Answer: B. catalytic site
14. The non-protein part of an enzyme that helps in catalysis is the:
Answer: C. cofactor
15. An enzyme that is active together with its cofactor is called a:
Answer: B. holoenzyme
16. The protein part of an enzyme that is inactive without its cofactor is the:
Answer: B. apoenzyme
17. Pepsin is secreted in the stomach as an inactive form called:
Answer: B. pepsinogen
18. Pepsinogen is converted into pepsin by:
Answer: C. HCl
19. The three types of cofactors are:
Answer: B. inorganic ions, organic molecules (coenzymes) and prosthetic groups
20. Inorganic ion cofactors are also called:
Answer: B. activators
21. Which of these is a metal ion cofactor for hexokinase?
Answer: B. Mg two plus
22. Coenzymes are generally derived from:
Answer: C. vitamins
23. Which of these is a coenzyme?
Answer: C. NAD plus
24. A prosthetic group is:
Answer: B. covalently bonded and permanently attached to the enzyme
25. An iron-containing porphyrin ring in cytochromes is an example of a:
Answer: C. prosthetic group
26. In the equation E + S, ES, EP, E + P the "ES" is called the:
Answer: B. enzyme-substrate complex
27. The lock and key model was proposed by:
Answer: B. Emil Fischer
28. The lock and key model was proposed in:
Answer: B. 1894
29. According to the lock and key model the enzyme active site is:
Answer: B. rigid
30. In the lock and key model, the lock represents the:
Answer: B. enzyme
31. Enzymes working according to the lock and key model are called:
Answer: C. non-regulatory enzymes
32. Sucrase and maltase follow the:
Answer: B. lock and key model
33. The ability of an enzyme to act on only one substrate is:
Answer: B. absolute specificity
34. Urease, which breaks down urea, shows:
Answer: B. absolute specificity
35. The induced fit model was proposed by:
Answer: B. Koshland
36. The induced fit model was proposed in:
Answer: B. 1959
37. In the induced fit model the active site is:
Answer: B. flexible and modified as the substrate approaches
38. Enzymes following induced fit are called:
Answer: B. regulatory or allosteric enzymes
39. Hexokinase is an example of an enzyme working by:
Answer: B. induced fit model
40. Carbonic anhydrase catalyses the reaction between:
Answer: B. carbon dioxide and water forming carbonic acid
41. The energy that must be supplied to make molecules react is the:
Answer: C. energy of activation
42. Enzymes speed up reactions by:
Answer: B. lowering the activation energy
43. Large amounts of heat cannot be used as activation energy in living systems because:
Answer: B. cells contain temperature-sensitive proteins
44. Living systems work in:
Answer: B. isothermal conditions
45. The rate of an enzymatic reaction is measured by:
Answer: B. amount of substrate changed or product formed in unit time
46. A 10 degree Celsius rise in temperature (up to a limit) generally:
Answer: C. doubles the rate
47. The temperature at which an enzyme shows maximum activity is the:
Answer: B. optimum temperature
48. Loss of catalytic activity of an enzyme due to high temperature is called:
Answer: C. denaturation
49. The bonds most sensitive to temperature change in an enzyme are the:
Answer: B. hydrogen bonds
50. Optimum temperature for most human enzymes is:
Answer: B. 37 to 38 degrees
About Biology Class 11 Unit 3 MCQs (Federal Board)
These 146 Biology MCQs cover Class 11 Unit 3: Enzymes of the Federal Board (FBISE) HSSC-I (1st Year / Class 11) syllabus. They are SLO-based MCQs as per the new pattern for FBISE exams. Each question has four options and the correct answer is shown, so you can practise for the annual examination and find the topics you still need to revise. The questions are split over 3 pages of 50. Use the Print button to save this chapter as a PDF.