MCQ on aminoacid with explanation set 4

MCQ on aminoacid with explanation set 4

Q) Which amino acid act as the precursor for the synthesis of the neurotransmitter serotonin?

a) Tyrosine
b) Tryptophan
c) Glycine
d) Arginine

Answer: option b

Q) Which amino acid act as the precursor of dopamine?

a) Glycine
b) Aspartate
c) Valine
d) Tyrosine

Answer: option d

Q) Amino acid which act as the precursor of IAA (indole 3-acetic acid) biosynthesis in plants is_____.

a) Tyrosine
b) Phenylalanine
c) Tryptophan
d) Methionine

Answer: option c

Explanation:

Indole-3-acetic acid is the naturally occurring auxin in plants. Several pathways of auxin biosynthesis in plants are known and in most of them, tryptophan acts as the precursor. Tryptophan independent biosynthesis of auxin is also known to science now. IAA is synthesized from the indole ring of tryptophan in the young leaves and shoots.

Q) Amino acid involved in urea cycle____.

a) Ornithine
b) Citrulline
c) Arginine
d) Both (a) and (b)
e) All of these

Answer: option e

Explanation:

Urea cycle (also called ornithine cycle): a biochemical cycle in many animals including human to produce urea from ammonia.

Urea cycle was the first discovered metabolic cycle by Hans Krebs and Kurt Henseleit in1932.

Q) Amino acid which act as the precursor of epinephrine synthesis is_____.

a) Glycine
b) Aspartate
c) Tyrosine
d) Valine

Answer: option c

Q) Which amino acid act as the precursor of nitric oxide biosynthesis in animals?

a) Phenyl alanine
b) Arginine
c) Aspartate
d) Ornithine

Answer: option b

Explanation:

Nitric oxide (NO) is one of the gaseous bio-signaling molecules in the cell. It is also called as Endothelium Derived Relaxing Factor (EDRF). NO is synthesized from the amino acid arginine by the enzyme nitric oxide synthase in the endothelial cells of blood vessels. NO is a vasodilating agent and it relaxes the smooth muscle cells and thereby enhances blood flow through blood vessels.

Q) Which of the following amino acid act as inhibitory neurotransmitter?

a) Glycine
b) Alanine
c) GABA
d) All of these

Answer: option d

Explanation:

Inhibitory amino acid neurotransmitters (IAA): GABA, Glycine, β-Alanine, Taurine

Q) Which of the following amino acid act as excitatory neurotransmitter?

a) Glutamate
b) Aspartate
c) Cysteine
d) All of these

Answer: option d

Explanation:

Excitatory amino acid neurotransmitters (EAA): L-Glutamate, L-Aspartate, L-Cysteine and L-Homocysteine

Q) Which amino acid act as the precursor of nucleotide biosynthesis?

a) Aspartate
b) Glycine
c) Glutamine
d) Both (a) and (b)
e) All of these

Answer: option e

Q) Total number of proteinogenic (protein building) amino acids in the living world is ____.

a) 20
b) 21
c) 22
d)23

Answer: option c

Explanation:

  • There are a total of 22 protein coding amino acids, among these 20 are coded by standard genetic code (standard amino acids).
  • The remaining two amino acids (Selenocysteine and Pyrrolysine) are coded by two stop codons.
  • Selenocysteine is considered as the 21st amino acid coded by UGA codon.
  • Pyrrolysine is considered as the 22nd amino acid coded by UAG codon

 

 

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