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Biomolecules · Question 65

AIPMT 2000MCQEasy📈 Topic in 12% papers+4−1
1

How do enzymes increase the rate of reactions?

  1. by lowering activation energy
  2. by increasing activation energy
  3. by changing equilibrium constant
  4. by forming enzyme substrate complex.

Answer

(1) by lowering activation energy

Solution

∵ As per NCERT, enzymes are biocatalysts; like any catalyst, an enzyme provides an alternative pathway and reduces the magnitude of the activation energy.

⇒ A larger fraction of molecules can cross the energy barrier, so the rate increases.

A catalyst does not change the equilibrium constant; it only helps equilibrium to be reached faster.

∴ Enzymes increase the rate of reactions by lowering activation energy.

Answer: (1)

AIPMT 2000

Keep practising — Biomolecules

2

The correct statement with regard to the secondary structure of DNA/RNA is :

  1. DNA possesses a double strand helix structure and contains thymine as one of the four bases
  2. DNA possesses a single strand helix structure and contains uracil as one of the four bases
  3. RNA possesses a double strand helix structure and contains uracil as one of the four bases
  4. RNA possesses a single strand helix structure and contains thymine as one of the four bases
NEET (UG) 2026
3

The correct statement about peptides and proteins is

  1. In -helices, the polypeptide chain is twisted into a left-handed screw (helix) through intramolecular hydrogen bonds
  2. Tertiary structure of proteins has two or more polypeptide subunits
  3. Only the proteins having a quaternary structure are biologically active
  4. In -pleated sheet structures, peptide chains are held together by intermolecular hydrogen bonds
RE-NEET (UG) 2026
4

The amino acid that gives a red-blood colour on treating its sodium fusion extract with sodium nitroprusside is

  1. serine
  2. leucine
  3. threonine
  4. methionine
RE-NEET (UG) 2026
5

Match the vitamins in List I with their sources in List II

  1. A-III, B-I, C-IV, D-II
  2. A-II, B-III, C-IV, D-I
  3. A-IV, B-I, C-II, D-III
  4. A-IV, B-II, C-I, D-III
RE-NEET (UG) 2026
6

Sugar 'X' A. is found in honey B. is a keto sugar C. exists in and -anomeric forms. D. Is laevorotatory. 'X' is :

  1. Maltose
  2. Sucrose
  3. D-Glucose
  4. D-Fructose
NEET (UG) 2025
7

Match List-I with List-II. Choose the correct answer from the options given below:

  1. A-II, B-III, C-I, D-IV
  2. A-IV, B-III, C-II, D-I
  3. A-I, B-III, C-II, D-IV
  4. A-IV, B-III, C-I, D-II
NEET (UG) 2025
8

The reagents with which glucose does not react to give the corresponding tests/products are Choose the correct options from the given below:

  1. B and C
  2. A and D
  3. B and E
  4. E and D
NEET (UG) 2024
9

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

  1. Statement I is true but Statement II is false.
  2. Statement I is false but Statement II is true.
  3. Both Statement I and Statement II are true.
  4. Both Statement I and Statement II are false.
RE-NEET (UG) 2024
10

Given below are two statements: In the light of the above statements, choose the correct answer from the options given below:

  1. Both Statement I and Statement II are false
  2. Statement I is true but Statement II is false
  3. Statement I is false but Statement II is true
  4. Both Statement I and Statement II are true
NEET (UG) 2023
11

The incorrect statement regarding enzymes is

  1. Enzymes are biocatalysts.
  2. Like chemical catalysts enzymes reduce the activation energy of bio processes.
  3. Enzymes are polysaccharides.
  4. Enzymes are very specific for a particular reaction and substrate.
NEET (UG) 2022

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