Ribose is an aldopentose. It contains an aldehydic group and five carbon atoms.

They are mirror images of each other hence, are enantiomers. They are aldohexoses too ( aldehyde group + six carbon ).

In option (B), two monosaccharides are held together by a glycosidic linkage between $$C{\text{ - }}1$$  of $$\alpha $$ - glucose and $$C{\text{ - 2}}$$  of $$\beta $$ - fructose.

$$DNA$$  has a double helical structure. These helix contains polynucleotide chains and these chains are held together by hydrogen bonds. In these polynucleotide chain of $$DNA,$$  adenine has thymine opposite to it and guanine has cytosine opposite to it.

A sequence of three nucleotides in messenger $$RNA$$  makes a codon for an amino acid because four bases in messenger $$RNA$$  adenine, cytosine, guanine and uracil have been shown to act in the form of triplet.

$$D{\text{ - }}\left( + \right){\text{ - }}$$  glucose contains aldehydic group which reacts with hydroxyl amine $$\left( {N{H_2}OH} \right)$$   to yield an oxime. The complete reaction is

The two polynucleotide chains of $$DNA$$  molecules are twisted around a common axis but run in opposite directions to form a right handed helix. The two chains are joined together by specific hydrogen bonds.

Vitamin $$A, D$$  are absorbed from the intestine by fats.

Sucrose is formed by the condensation of $$\alpha {\text{ - }}D{\text{ - }}$$ glucopyranose and $$\beta {\text{ - }}D{\text{ - }}$$ fructofuranose.

Starch is a mixture of two components, one is water soluble component called amylose (20%) and another is water insoluble component called amylopectin (80%).