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Chemistry · 2023 · 4 marks
CBSE 2023 · Region 2 · Set 1 · Q32
Carbohydrates are optically active polyhydroxy aldehydes and ketones. They are also called saccharides. All those carbohydrates which reduce…
Carbohydrates are optically active polyhydroxy aldehydes and ketones. They are also called saccharides. All those carbohydrates which reduce Fehling's solution and Tollen's reagent are referred to as reducing sugars. Glucose, the most important source of energy for mammals, is obtained by the hydrolysis of starch. Vitamins are accessory food factors required in the diet. Proteins are the polymers of $\displaystyle \alpha$-amino acids and perform various structural and dynamic functions in the organisms. Deficiency of vitamins leads to many diseases. Answer the following:
(a)
The penta-acetate of glucose does not react with Hydroxylamine. What does it indicate?
(b)
Why cannot vitamin C be stored in our body?
(c)
Define the following as related to proteins:
(i)
Peptide linkage
(ii)
Denaturation
OR
(c)
Define the following as related to carbohydrates:
(i)
Anomers
(ii)
Glycosidic linkage $\displaystyle \mathbf{2} \boldsymbol{\times} \mathbf{1}$
Marking-scheme solution
(a) Absence of free - CHO group.
(b) Because being water soluble it is excreted through urine.
(c) (i) -CONH- linkage between two amino acids.
(ii) Loss of biological activity when protein is subjected to change in temperature, pH, etc.
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CBSE Class 12 Chemistry past-paper question from the 2023 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.