Unit 14 Biomolecules (Intext Questions-3)
Intext Questions
14.6 Why cannot vitamin C be stored in our body?
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Answer
Vitamin ${C}$ cannot be stored in our body because it is water soluble. As a result, it is readily excreted in the urine.
14.7 What products would be formed when a nucleotide from DNA containing thymine is hydrolysed?
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Answer
When a nucleotide from the DNA containing thymine is hydrolyzed, thymine $\beta$-D-2-deoxyribose and phosphoric acid are obtained as products.
14.8 When RNA is hydrolysed, there is no relationship among the quantities of different bases obtained. What does this fact suggest about the structure of RNA?
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Answer
A DNA molecule has two strands in which the four complementary bases pair each other, i.e. cytosine $({C})$ always pairs with guanine $({G})$ while thymine ( T ) always pairs with adenine (A). Therefore, when a DNA molecule is hydrolysed, the molar amounts of cytosine is always equal to that of guanine and that of adenine is always equal to that of thymine. Since in RNA there is no relationship between the quantities of four bases (C, G, A and U) obtained, therefore, the base-pairing principle, i.e., A pairs with U and C pairs with G is not followed. Therefore, unlike DNA, RNA has a single strand.
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