Enzymes Mdcat Mcqs Online Test 1

Instructions for Chapter Enzymes Online Test Mdcat-2023:

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Test Details:

Subject: Biology
Class: 1st year or 11
Chapter name: Enzyme
Test: MDCAT 2023
Book: Sindh Textbook
Total No. Of MCQS: 50
Time Allowed: 50 Minutes

1014

Created on July 11, 2023 By

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Mdcat Biology XI Enzymes Mcqs test 1

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NameEmailPhone Number

1 / 50

1. In an endergonic reaction:

a) the reactants contain more free energy than the products

b) the products contain more free energy than the reactants

c) no activation energy is required

d) catalysis cannot occur

2 / 50

2. The concept of “Ribozymes” was given by:

a) Fisher 1898

b) Friedrich Wilhelm Kuhne 1878

c) Koshland 1955

d) Thomas Cech & Sidney Altman 1980

3 / 50

3. Most enzymatic pathways are regulated by

a) Feedback inhibition

b) Positive feedback inhibition

c) Concentration of enzymes inhibition None of these

d) None of these

4 / 50

4. Substrate and enzyme once the product is consumed the inhibition also _________ and form _________ product

a) Reduced , Less

b) Increase , More

c) Reduced , More

d) Increase , Less

5 / 50

5. Which of the following is true regarding competitive and noncompetitive inhibition?

a) Both can be overcome by increasing the substrate concentration

b) Competitive inhibition induces changes to the active site

c) Noncompetitive inhibition has no effect on the enzyme affinity for substrates

d) none

6 / 50

6. The term Enzymes are coined by

a) Whelium Kuhne

b) Buchner

c) Wiliamson Kuhne

d) Paustre

7 / 50

7. Mg +2 is an inorganic activator for enzymes:

a) Phosphatase

b) Carbonic anhydrase

c) Amylase

d) Enterokinase

8 / 50

8. An uncatalyzed reaction involved:

a) High activation energy

b) Low activation energy

c) Balanced activation energyAll of these

d) none

9 / 50

9. Which of the following is produced with the combination of apoenzyme and coenzyme:

a) Holoenzyme

b) Enzyme substrate complex

c) Prosthetic group

d) Enzyme product complex

10 / 50

10. The inhibition caused by the final end product of reaction is called

a) Non competitive inhibition

b) Competitive inhibition

c) Allosteric inhibition

d) All of these

11 / 50

11. All are correct for active sites EXCEPT?

a) Carry catalytic activity

b) Have particular binding sites

c) Work in feedback inhibition

d) Consumed during action

12 / 50

12. Which of the followings is(are) the co-factor(s) for an enzyme.

a) ATP

b) vitamins

c) minerals

d) both a and b

13 / 50

13. Cofactors:

a) Break hydrogen bonds in proteins

b) Help facilitate enzyme activity

c) Increase activation energy

d) Are very rare in living organisms

14 / 50

14. Nicotinamide adenine dinucleotide NAD+ is:

a) An enzyme

b) A coenzyme

c) An active site

d) An activator

15 / 50

15. What is correct for apo-enzyme.

a) A simple enzyme

b) A covalently bonded non-protein part of a conjugated enzyme

c) An inorganic co-factor of a conjugated enzyme

d) Protein part of a conjugated enzyme

16 / 50

16. Enzymes are functional:

a) Inside the cell

b) Outside the cell

c) Both are posible

d) No fixed proportion

17 / 50

17. Which is correct for enzymes?

a) Lower the activation energy of a reaction

b) Are specific in their choice of substrates

c) Tolerable to the change in temperature

d) both a and b

18 / 50

18. A catalyst will make a reaction

a) stop

b) slow down

c) speed up

d) go in any different direction

19 / 50

19. All of the following are correct for enzymes EXCEPT:

a) Most enzymes are protein molecules

b) Ever chemical reaction in a cell requires a specific enzyme

c) Enzymes speed up a chemical reaction

d) Generally enzymes are named after the products they form.

20 / 50

20. Competitive inhibitor overcome by adding substrate show that :

a) Enzymes are pH dependent

b) Enzymes are made up of protein

c) Enzymes are biocatalysts

d) Enzymes are specific in nature

21 / 50

21. In non-competitive inhibition the extent of inhibition depends only on

a) concentration of enzyme

b) concentration of substrate

c) concentration of inhibitor

d) concentration of ES complex

22 / 50

22. All coenzyme are derived from:

a) Protein

b) Carbohydrates

c) Nucleic acid

d) Vitamins

23 / 50

23. Which of the following comprises of inorganic ions :

a) Coenzyme

b) Prosthetic group

c) Activators

d) Apoenzyme

24 / 50

24. Enzymes are generally inactivited rapidly by exposure to UV high and also alpha , beta rays because it's alters the :

a) Quantity of enzymes

b) pH of enzymes

c) Shape of enzymes

d) Temperature of enzymes

25 / 50

25. At about 0°C most enzymes are:

a) Inactive

b) Active

c) Destroyed

d) Replicated

26 / 50

26. A coenzyme constitute about certain % of portion of entire enzyme.

a) 5%

b) 1%

c) 2%

d) 3%

27 / 50

27. In the lock and key model of enzyme action, the part of enzymes recognizes the substrate is known as :

a) Enzyme substrate complex

b) Products

c) Enzyme product complex

d) Active site

28 / 50

28. DDT are inhibitors of key enzymes in :

a) Nervous system

b) Respiratory system

c) Digestive system

d) Circulatory system

29 / 50

29. Parathion are ___________.

a) Inhibitor

b) Activators

c) Enzymes

d) All of these

30 / 50

30. Enzymes minus it's coenzyme is referred to as the :

a) Iso enzymes

b) Metalloenzymes

c) Apoenzyme

d) All of these

31 / 50

31. Optimum pH value for pepsin is :

a) . 5.5

b) 4.1

c) 1.4

d) 2.7

32 / 50

32. Competitive inhibitor stop an enzymes from working by ;

a) Change the shape of enzymes

b) Merging with the substrate instead

c) Blocking the active site of enzymes

d) Combining with the product of reaction

33 / 50

33. Every Enzymes function effectively at :

a) 9 pH

b) Optimum pH

c) 2 pH

d) 7 pH

34 / 50

34. The reversible inhibitors constitute :

a) No linkage with enzymes

b) Weak linkage with enzymes

c) Medium linkage

d) Strong linkage with enzymes

35 / 50

35. The non-protein part of an enzyme is called

a) coenzyme

b) cofactor

c) substrate

d) activator

36 / 50

36. Which molecule binds with the active site of enzyme?

a) Protein

b) Nucleic acid

c) Substrate

d) None

37 / 50

37. The structure of enzyme consists of:

a) three dimensional globular protein molecules

b) nucleic acid

c) both a and b

d) none

38 / 50

38. The reactants of enzymatic reactions are called:

a) substrates

b) products

c) output

d) none

39 / 50

39. Enzyme have enormous power of :

a) magnetic power

b) chemical power

c) catalytic power

d) electric power

40 / 50

40. What is the meaning of an enzyme?

a) Biological catalyst

b) Accelerate a specific chemical reaction

c) Lowering the activation energy in the reaction

d) All of the above

41 / 50

41. Which are biological catalysts?

a) Proteins

b) Enzymes

c) Molecules

d) Compounds

42 / 50

42. Lock and Key model was proposed by

a) Emil Fischer

b) Koshland

c) Robin Williams

d) Rudolph Virchow

43 / 50

43. A three-dimensional cavity bearing a specific charge by which the enzyme reacts with its substrate is called

a) Active site

b) Binding site

c) Catalytic site

d) Allosteric site

44 / 50

44. Enzymes _________ the activation energy of a chemical reaction

a) Increases

b) Decreases

c) Does not effect

d) Increases or decreases depending upon individual enzyme

45 / 50

45. Which one forms the raw material for coenzymes?

a) Vitamins

b) Carbohydrates

c) Proteins

d) Metals

46 / 50

46.

An activated enzyme consisting of the polypeptide chain and a cofactor is called:

a) Apoenzyme

b) Holoenzyme

c) Conjugate enzyme

d) Both B and C

47 / 50

47. Which statement about enzyme is incorrect:

a) Some of them consist solely of protein with no non-protein part.

b) They catalyze a chemical reaction without being utilized

c) All enzymes are fibrous Proteins

d) They without their cofactor are called apoenzyme.

48 / 50

48. Biological molecules (proteins) which catalyze a biochemical reaction and remain unchanged after completion of reaction are called

a) Cofactor

b) Coenzymes

c) Activator

d) Enzymes

49 / 50

49. Zinc plays important role as activator for which of the following enzymes?

a) Hexokinase

b) Carboxylase

c) Carbonic anhydrase

d) Phosphorylase

50 / 50

50. In certain enzymatic pathways, _______ act as inhibitors.

a) Substrates

b) End products

c) Coenzymes

d) Activators

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The average score is 63%

Instructions for Chapter Enzymes Online Test Mdcat-2023:

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