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MODEL PAPER 6 — Chemistry STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceChemistryMODEL PAPER 65 Marks
Question
(a) Differentiate between
a. Nucleotide and Nucleoside
b. Amylose and Amylopectin
(b) Write a reaction which shows that all the carbon atoms in glucose are linked in a straight chain.
(c) Write two differences between DNA and RNA.
(d) Amino acids can be classified as $\alpha-, \beta-, \gamma-, \delta-$ and so on depending upon the relative position of the amino group with respect to the carboxyl group. Which type of amino acids forms a polypeptide chain in proteins?
(e) What are any two good sources of vitamin A?
(f) What is anomeric carbon?
(g) What is the difference between a glycosidic linkage and a peptide linkage?
✓

Answer

Attempt any five of the following:
(i)
a. Nitrogeneous base linked with pentose sugar called as nucleoside while Nucleoside linked with phosphate group is called as nucleotide.
b. Amylose is water soluble while amylopectin is water insoluble.
(ii) On prolonged heating with HI, glucose gives n-hexane which suggest that all the six carbon atoms in glucose are linked linearly.
HOH_2 $HOH _2 C \underset{\text { Glu cose }}{( CHOH )_4 CHO }+ HI \xrightarrow{\Delta} CH _3\left( CH _2\right)_4 CH _3$
(iii) 
DNARNA
Double strandedSingle stranded
Thymine base is presentUracil base is present

Image
(v) Milk, carrot
(vi)An anomeric carbon can be identified as the carbonyl carbon (of the aldehyde or ketone functional group) in the open- chain form of the sugar. It can also be identified as the carbon bonded to the ring oxygen and a hydroxyl group in the cyclic form.
(vii) Glycosidic linkage: It is the linkage which joins two monosaccharides through oxygen atom. It is present in carbohydrates.
Peptide Linkage: It is the linkage which joins two amino acids through - CO-NH- bond. It is present in proteins.

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