(i) Deficiency of which vitamin causes poor coagulation of blood? [1] (ii) Write the structure of zwitterion o

Question 44 of 49

Q. (i) Deficiency of which vitamin causes poor coagulation of blood? [1]

(ii) Write the structure of zwitterion of alanine. [1]

(iii) What do you understand by the term 'glycosidic linkage'? [1]

West Bengal WbchseWest Bengal HS (WBCHSE) Board 2025Subjective· 3mImportance★★★★★

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Vitamin K → blood clotting; alanine's zwitterion carries both $-NH_3^+$ and $-COO^-$ ; a glycosidic linkage joins two sugar units via an oxygen bridge.

(i) Vitamin K is essential for the synthesis of prothrombin and other clotting factors in the liver. Its deficiency impairs the blood clotting cascade, causing poor coagulation of blood (excessive bleeding/bruising).

(ii) Amino acids exist predominantly as internal salts (zwitterions/dipolar ions) at physiological/neutral pH, in which the basic amino group is protonated and the acidic carboxyl group is deprotonated, while the molecule as a whole carries no net charge. For alanine ( $CH_3CH(NH_2)COOH$ ), the zwitterion is:

$CH_3-CH(NH_3^+)-COO^-$

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Same / Similar Concept — real previous-year questions on the same or a closely similar concept, not this exact question.

CBSE 2026Set SEM31 markMCQ
$Q. At isoelectric point structure of glycine is$
(a) H2N-CH2-COOH
(b) H2N-CH2-COO(-)
(c) H3N(+)-CH2-COOH
(d) H3N(+)-CH2-COO(-)
›Reveal solutionSolution

At the isoelectric point an amino acid carries no net charge and exists as a zwitterion, with -COOH deprotonated and -NH2 protonated. Correct option (d).

In an amino acid the -COOH group loses a proton and the -NH2 group gains it, giving an internal salt (zwitterion). At the isoelectric point the positive and negative charges balance so the net charge is zero and the molecule does not migrate in an electric field.

…

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CBSE 2022Set ANNUAL1 markMCQ
$Q. Insulin is$
(a) an amino acid
(b) a protein
(c) a carbohydrate
(d) a lipid OR Hydrolysis of protein produces .......... number of amino acids.
(a) 15
(b) 20
(c) 25
(d) 35
›Reveal solutionSolution

Insulin is a peptide hormone made of two polypeptide chains linked by disulfide bonds, making it a protein.

Reasoning: Insulin is a hormone secreted by the beta-cells of the pancreas that regulates blood glucose levels. Structurally, it consists of two polypeptide chains (the A-chain and B-chain, made of amino acids joined by peptide bonds) held together by disulfide (-S-S-) bridges. Since it is built from amino acids linked by peptide bonds, insulin is classified biochemically as a prote …

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CBSE 2022Set ANNUAL1 markMCQ
$Q. Optically inactive compound is$
(a) Aspartic acid
(b) Lysine
(c) Cystine
(d) Glycine
›Reveal solutionSolution
Optical activity requires a chiral (asymmetric) carbon; glycine's alpha-carbon carries two identical hydrogen substituents, so it has no chiral centre and is optically inactive.

Reasoning: An amino acid's alpha-carbon is chiral (and hence the amino acid is optically active) only if it bears four different groups: -NH2, -COOH, -H, and a side chain (R group) that is different from H.

Aspartic acid, Lysine, and Cystine all have side chains different from hydrogen (a -CH2COOH, a -(CH2)4NH2, and a -CH2SSCH2- linked side chain respectively), so their alpha-carbons are genuinely chiral centres — these are optically active. …
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Q.(i) Deficiency of which vitamin causes poor coagulation of blood? [1]

Concept understanding — Amino Acids and the Peptide Bond

Q.(i) Deficiency of which vitamin causes poor coagulation of blood? [1]

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