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Which is correct statement : -
A
Starch is polymer of $\alpha$-glucose
B
Amylose is a component of cellulose
C
Proteins are composed of only one type of amino acid
D
In cyclic structure of fructose, there are four carbons and one oxygen atom
Detailed Solution
Starch is a polymer of $\alpha$-D-glucose. It has two components: amylose (unbranched, $\alpha$-1,4 links) and amylopectin (branched, with $\alpha$-1,6 links as well). Correct.
Amylose is a component of starch, not cellulose (cellulose is made of $\beta$-glucose).
Proteins are made of many different amino acids (about 20 types).
In the furanose (cyclic) form of fructose, the five-membered ring has four carbons and one oxygen. (This statement is also true for the ring itself, but the key takes the starch statement as the correct one; fructose has six carbons in total.)
So, as per the answer key, the correct statement is that starch is a polymer of $\alpha$-glucose.
Amylose is a component of starch, not cellulose (cellulose is made of $\beta$-glucose).
Proteins are made of many different amino acids (about 20 types).
In the furanose (cyclic) form of fructose, the five-membered ring has four carbons and one oxygen. (This statement is also true for the ring itself, but the key takes the starch statement as the correct one; fructose has six carbons in total.)
So, as per the answer key, the correct statement is that starch is a polymer of $\alpha$-glucose.