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Biomolecules (Biology) · Question 54

AIPMT 2014MCQMedium📈 Topic in 38% papers+4−1
1

Select the option which is not correct with respect to enzyme action.

  1. Substrate binds with enzyme at its active site.
  2. Addition of a lot of succinate does not reverse the inhibition of succinic dehydrogenase by malonate.
  3. A non-competitive inhibitor binds the enzyme at a site distinct from that which binds the substrate.
  4. Malonate is a competitive inhibitor of succinic dehydrogenase.

Answer

(2) Addition of a lot of succinate does not reverse the inhibition of succinic dehydrogenase by malonate.

Solution

As per NCERT, malonate closely resembles succinate in structure and inhibits succinic dehydrogenase by competing with succinate for the active site (competitive inhibition).

∵ In competitive inhibition, increasing the substrate concentration out-competes the inhibitor.

⇒ Adding a lot of succinate reverses the inhibition by malonate.

∴ The statement that it does not reverse the inhibition is not correct.

Answer: (2)

AIPMT 2014

Keep practising — Biomolecules (Biology)

2

Which one of the following is a non-reducing carbohydrate?

  1. Maltose
  2. Sucrose
  3. Lactose
  4. Ribose 5-phosphate
AIPMT 2014
3

A phosphoglyceride is always made up of

  1. a saturated or unsaturated fatty acid esterified to glycerol molecule to which a phosphate group is also attached.
  2. a saturated or unsaturated fatty acid esterified to a phosphate group which is also attached to a glycerol molecule.
  3. only a saturated fatty acid esterified to a glycerol molecule to which a phosphate group is also attached.
  4. only an unsaturated fatty acid esterified to a glycerol molecule to which a phosphate group is also attached.
NEET 2013
4

Macromolecule chitin is

  1. sulphur containing polysaccharide
  2. simple polysaccharide
  3. nitrogen containing polysaccharide
  4. phosphorus containing polysaccharide.
NEET 2013
5

Transition state structure of the substrate formed during an enzymatic reaction is

  1. transient and unstable
  2. permanent and stable
  3. transient but stable
  4. permanent but unstable.
NEET 2013
6

The essential chemical components of many coenzymes are

  1. carbohydrates
  2. vitamins
  3. proteins
  4. nucleic acids.
NEET 2013
7

Which of the following statements about enzymes is wrong?

  1. Enzymes are denaturated at high temperatures.
  2. Enzymes are mostly proteins but some are lipids also.
  3. Enzymes are highly specific.
  4. Enzymes require optimum pH and temperature for maximum activity.
NEET 2013 (Karnataka)
8

Uridine, present only in RNA is a

  1. nucleoside
  2. nucleotide
  3. purine
  4. pyrimidine.
NEET 2013 (Karnataka)
9

The figure shows a hypothetical tetrapeptide portion of a protein with parts labelled A - D. Which one of the following options is correct? [figure]

  1. D is an acidic amino acid-glutamic acid.
  2. C is an aromatic amino acid-tryptophan.
  3. A is the C-terminal amino acid and D is N-terminal amino acid.
  4. A is a sulphur containing amino acid methionine.
NEET 2013 (Karnataka)
10

Which one of the following biomolecules is correctly characterized?

  1. Lecithin – a phosphorylated glyceride found in cell membrane.
  2. Palmitic acid – an unsaturated fatty acid with 18 carbon atoms.
  3. Adenylic acid – adenosine with a glucose phosphate molecule.
  4. Alanine amino acid – contains an amino group and an acidic group anywhere in the molecule.
AIPMT 2012 (Mains)
11

For its activity, carboxypeptidase requires

  1. Zinc
  2. iron
  3. niacin
  4. copper
Out of syllabusAIPMT 2012 (Mains)

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