NEET Practice Questions (MCQs) with Answers & Solutions

(b) The a-d-glucose and b-D-glucose are isomers called anomers. The isomer having the hydroxyl group(-OH) on the right is called a-d-glucose and one having the hydroxyl group(-OH) on the left is called b-D-glucose. Such pairs of optical isomers which differ in the configuration only around C₁ atom are called anomers.

(a) Glycolysis is the first stage in the oxidation of glucose. It is an anaerobic process and involves the degradation of glucose into two molecules of pyruvate with the generation of two molecules of ATP.

(c) The aqueous solution of sucrose is dextrorotatory having ${\left[\mathrm{\alpha }\right]}_D=+66.4°$. On hydrolysis with dilute acids or enzyme invertase, cane sugar(sucrose) gives equimolar mixture of D(+)-glucose and D-(-)-fructose

$$\begin{gathered} {\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11} + {\mathrm{H}}_2\mathrm{O} \stackrel{ \mathrm{HCl} }{\to } {\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6 + {\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6 \\ \mathrm{cane} \mathrm{sugar} \mathrm{D}-\mathrm{glucose} \mathrm{D}-\mathrm{fructose} \\ [\mathrm{\alpha }{]}_D=66.4° [\mathrm{\alpha }{]}_D=+52.5 [\mathrm{\alpha }{]}_D=-92.4° \end{gathered}$$

So, sucrose is dextrorotatory but after hydrolysis gives dextrorotatory glucose and laevorotatory fructose. D-(-)-fructose has a greater specific rotation than D-(+)-glucose. Therefore, the resultant solution is laevorotatory in nature with specific rotation of -39.9$°$.

(a) The number of molecules of ATP (Adenosine triphosphate) produced in lipid metabolism of a molecule of palmitic acid is 130. Monosacchride ribose is an ATP. which acts as energy currency of the cells during metabolism of carbohydrates, protein and fats.

(b) The organic compounds other than carbohydrates, proteins which maintain normal growth and nutrition in the human body (but not produced in human body) are called vitamins.

(c) Digestion is basically hydrolysis reaction in which large molecules are hydrolysed to give smaller molecules. For example when we eat proteins, it will hydrolyse and form amino acids.

(d) All living cells contains nucleoproteins, i.e. substances made up of proteins combined with biopolymers (known as nucleic acids). Nucleic acids are biologically important polymers which are present in all living cells. DNA is the polymer of nucleotides.

(a) Glucagon is a peptide hormone because in it peptide linkage is present.

Fact

Non-reducing sugars do not have an OH group attached to the anomeric carbon so they cannot reduce other compounds. All monosaccharides such as glucose are reducing sugars. A disaccharide can be a reducing sugar or a non-reducing sugar. Maltose and lactose are reducing sugars, while sucrose is a non-reducing sugar.