Biomolecules Test

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Biomolecules Test - 81

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Weekly Quiz Competition

Question 1
1 / -0

In the study of enzymes, a sigmoidal plot of substrate concentration(S) versus the reaction velocity(V) indicates

A
Michaelis- Menten kinetics

B
Cooperative binding

C
Competitive inhibition

D
Non-Competitive inhibition
Solution
- Two 20th century scientists, Leonor Michaelis and Maud Leonora Menten proposed the model known as Michaelis-Menten Kinetics to explain the gross mechanism of enzyme-catalyzed reactions.
- According to Michaelis- Menten kinetics, when we plot a graph, with substrate concentration on the X-axis and corresponding velocity on the Y axis, it can be observed from the graph that as the concentration of the substrate increases, there is a corresponding increase in the V$$_0$$.
- However, beyond a particular substrate concentration, the velocity remains constant without any further increase. The resultant curve is sigmoidal.
- This maximum velocity of an enzyme catalysed reaction under substrate saturation is called the Vmax, maximum velocity.
So, the correct answer is option A.
Question 2
1 / -0

All enzymes of TCA cycle are located in the mitochondrial matrix except one which is located in inner mitochondrial membranes in eukaryotes and in cytosol in prokaryotes. This enzyme is?

A
Lactate dehydrogenase

B
Isocitrate dehydrogenase

C
Malate dehydrogenase

D
Succinate dehydrogenae
Solution
Correct Option: D
Explanation:
All enzymes of Tricarboxylic acid (TCA) cycle are present in mitochondrial matrix except succinate dehydrogenase.
Succinate dehydrogenase is tightly bound to the inner mitochondrial membrane in eukaryotes and to the plasma membrane in prokaryotes.
It has three different iron-sulphur clusters and one covalently bound Flavin adenine dinucleotide (FAD).
Before entering electron transport system (ETS) in mitochondria, the electrons pass from succinate through the FAD and iron-sulphur centres.
Hence, this enzyme is succinate dehydrogenae.
Question 3
1 / -0

The following tripeptide can be represented as.

A
$$Tyr-Val-Thr$$

B
$$Phe-Ala-Ser$$

C
$$Phe-Leu-Cys$$

D
$$Lys-Ala-Ser$$

Solution

The given tripeptide can be represented as $$Phe-Ala-Ser$$.
$$Phe$$ $$ \displaystyle = $$ $$phenylalanine$$
$$Ala$$ $$ \displaystyle = $$ $$alanine$$
$$Ser$$ $$ \displaystyle = $$ $$serine$$
Question 4
1 / -0

In the study of enzymes, a sigmoid plot of ___________ may indicate Michaelis-Menten kinetics.

A
Substrate concentration[s] versus reaction velocity[v]

B
Product concentration[p] versus reaction velocity[v]

C
Substrate concentration[s] versus product concentration[p]

D
Substrate concentration[s] versus enzyme concentration[e]
Question 5
1 / -0

Among the following L-serine is:

A

B

C

D
Question 6
1 / -0

Which of the following categories of macromolecules includes representatives that frequently serve as energy storage molecules?

A
Proteins

B
Lipids

C
Carbohydrates

D
Both lipids and carbohydrates

Solution

Energy storage molecules are those molecules which store energy in the form of covalent chemical bonds. Some molecules like glycogen (carbohydrate) and triglycerides (lipids) are synthesized by the cells and they are stored for the later release of energy. So, the correct answer is "both lipids and carbohydrates".
Question 7
1 / -0

Of the following chemicals, which one is used as a substitute for sugar?

A
Insulin

B
Saccharin

C
Vanilla

D
Casein

Solution
Question 8
1 / -0

The shape of an enzyme, and consequently its activity, can be reversibly altered from moment to moment by

A
Amino acid substitutions

B
Allosteric subunits

C
Sulphur substitutions

D
High pH

Solution

Allosteric subunits attach invariably to the enzyme other than at its active site, causing a change in the shape of the enzyme and consequently affecting its activity.
So, the correct option is 'Allosteric subunits'.
Question 9
1 / -0

Which one out of A - D given below correctly represents the structural formula of a basic amino acid?

A
C

B
D

C
A

D
B

Solution

A. It is the structure of glutamic acid which is a acidic amino acid.
B. It is the structure of serine which is a neutral amino acid.
D. It is the structure of lysine which is a basic amino acid. These have 2 amino group and 1 carboxyl group.
So, the correct answer is 'D'.
Question 10
1 / -0

Given are the structures of cyclic D-glucoside.

Moles of $$HCHO$$ formed are:

A
$$1, 1$$

B
$$2, 2$$

C
$$1, 2$$

D
$$2, 1$$

Solution

$$\bullet $$ Both $$X$$ and $$Y$$ gives $$1,1$$ moles of $$HCHO$$ respectively.
$$\bullet $$ Cleavage of glycolic bond by $${ HIO }_{ 4 }$$ :-
Converts alcohol $$\rightarrow$$ Carbonyl
Carbonyl $$\rightarrow$$ acid.