Enzymes MCQs

Question 1

The optimum pH for the functioning of enzyme pepsin is:

Accepted Answer

2

Answer

3

Answer

4

Answer

5

Question 2

The complex that forms when a substrate binds to an enzyme is called:

Accepted Answer

Enzyme-substrate complex

Answer

Enzyme complex

Answer

Substrate complex

Answer

Structural complex

Question 3

If more substrate is added to an already occurring enzymatic reaction, then more enzyme activity is seen because of which of the following?

Accepted Answer

There is probably more enzyme available than there is substrate

Answer

There is probably more substrate present than there is enzyme

Answer

There is probably more product present than there is either substrate or enzyme

Answer

The enzyme-substrate complex is probably failing to form during the reaction

Question 4

Enzyme-substrate specificity is a result of which property of the enzyme?

Accepted Answer

Tertiary structure of enzymes

Answer

Primary structure of enzymes

Answer

Secondary structure of enzymes

Answer

Quarternary structure of enzymes

Question 5

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

Accepted Answer

Holoenzyme

Answer

Apoenzyme

Answer

Conjugated enzyme

Answer

Hybrid enzyme

Question 6

Catalysts that increase the rate of biological chemical reaction are called?

Accepted Answer

enzymes

Answer

proteins

Answer

vitamins

Answer

minerals

Question 7

Find the Error.A couple of my friends(A) has planned(B) to open(C) a travel agency, but they(D) have failed.

Accepted Answer

Has planned

Answer

A couple of my friends

Answer

To open

Answer

But they

Question 8

Find the error of Punctuation."Do you need somebody to go to the store." asked the boy, "maybe to get some milk or something."

Accepted Answer

Store

Answer

Do you need

Answer

Boy, maybe

Answer

Something

Question 9

In this section of logical deduction, the question consists of a brief passage (usually a report containing certain data regarding some social or economic problem), followed by certain inferences based on it. The student is required to analyze the contents (or data) of the passage and grasp the desirable facts from it. Then, student has to consider each of the given inferences in the context of the given passage. decide upon its degree of truth or falsity and then choose the hest alternative provided accordingly.The Government of Pakistan has urged to Provincial Governments to create more jobs opportunities for women. All-out efforts are to be made to have more training facilities for women so that they can be gainfully employed. It is in pursuance of the recent policy decisions taken by the Government to make women self-reliant. The Provincials have been asked to end discrimination against the fair sex so far new jobs are concerned. The wage for women workers should also the strictly adhered to. it has been emphasized.Women should he given higher wages than men to make them self-reliant.

Accepted Answer

Definitely false

Answer

Definitely true

Answer

Probably true

Answer

Data inadequate

Answer

Probably false

Question 10

In the following question, two statements numbered I and II are given. There may be cause and effect relationship between the two statements. These two statements may be the effect of the same cause or independent causes. These statements may be independent causes without saving any relationship. Read both the statements in question and mark your answer as:A. If statement I is the cause and statement II is its effect;B. If statement II is the cause and statement, I is its effect;C. If both the statements I and II are independent causes;D. If both the statements I and II are effects of independent causes;E. If both the statements I and II are effects of some common causes;I. There has been an increase in the underground water level column at all places in Lahore due to the last year's monsoon rains.II. Most of the trains were cancelled last year due to water-logging on the tracks.

Accepted Answer

E. If both the statements I and II are effects of some common cause;

Answer

A. If statement I is the cause and statement II is its effect;

Answer

B. If statement II is the cause and statement I is its effect;

Answer

C. If both the statements I and II are independent causes;

Answer

D. If both the statements I and II are effects of independent causes;

Question 11

The given graphs show the effects of temperature and pH on enzyme activity.Which of the given statements CORRECTLY matches the point on the graphs with the description of enzyme activity?

Accepted Answer

At point I, hydrogen bonds are formed between enzyme and substrate

Answer

At point II, kinetic energy of enzyme and substrate is the highest.

Answer

At point III, peptide bonds in the enzyme begin to break

Answer

At point IV, the enzyme is completely denatured

Question 12

The graph shows the effect of substrate concentration on the rate of an enzyme-catalysed reaction.The CORRECT interpretation of the graph is that between points:

Accepted Answer

Y and Z the number of enzyme molecules is limiting the rate of reaction

Answer

X and Y the number of enzyme molecules is limiting the rate of reaction

Answer

X and Y the number of product molecules is limiting the rate of reaction

Answer

Y and Z the number of substrate molecules is limiting the rate of reaction

Question 13

To evaluate the activity of salivary amylase enzyme, students collected samples (I, II, III andIV) of amylase-starch mixture at different times and added a drop of iodine reagent to each sample.The given table shows the resulting colours and the amount of starch remaining in each sample.Based on the resulting colours of the iodine test, the sample which shows the highest level of amylase activity is

Accepted Answer

III

Answer

I

Answer

II

Answer

IV

Question 14

Saqib performed the following steps in sequence as a part of an experiment.1) Added equal amounts of starch solution into two test tubes, I and II2) Added salivary amylase to test tube I and boiled amylase solution to test tube II3) Shook the test tubes and left them in a water bath for 10 minutes at 37°C4) Added a few drops of iodine solution to each test tubeHe observed that the contents of test tube I turned reddish yellow in color, and test tube II maintained its blue color.The CORRECT inference that he must have made based on his observations of test tube I and test tube II is

Accepted Answer

D

Answer

A

Answer

B

Answer

C

Question 15

The graph shows the rate of an enzyme-catalysed reaction at increasing substrateconcentrations.At which of the following point(s) do all active sites of the enzyme seem occupied?

Accepted Answer

Points II and III

Answer

Point I only

Answer

Point III only

Answer

Points I and II

Question 16

The given table shows the percentage of product formation in an enzyme-catalysed reaction at different temperatures.

Accepted Answer

D

Answer

A

Answer

B

Answer

C

Question 17

The given table shows the percentage of product formation in an enzyme-catalysed reaction at different temperatures. Which percentage of product formation shows optimum temperature?"

Accepted Answer

IV

Answer

I

Answer

II

Answer

III

Question 18

Which of the following statements about the lock and key model is INCORRECT?

Accepted Answer

The enzyme can react with a wide range of substrates

Answer

The active site is rigid in nature

Answer

The active site is complementary to substrate

Answer

The enzyme can react with specific substrates only

Question 19

The given graph shows the comparison of activation energy in hydrolysis of sucrose with and without an enzyme.

Accepted Answer

B

Answer

A

Answer

C

Answer

D

Question 20

Lock and key model was proposed by _?

Accepted Answer

Emil Fischer

Answer

Koshland

Answer

James Watson and Francis Crick

Answer

Rosalind Franklin

Free Enzymes MCQs with Answers