Biomolecules MCQs for NEET — Chemistry Questions with Answers

The NCERT text (BIOLOGY chapter) explicitly states, 'Based on number of amino and carboxyl groups, there are acidic (e.g., glutamic acid), basic (lysine) and neutral (valine) amino acids.' The Chemistry chapter further classifies, 'more carboxyl groups as compared to amino groups makes it acidic.'

The NCERT Biology text says, 'The R group in these proteinaceous amino acids could be a hydrogen (the amino acid is called glycine), a methyl group (alanine), hydroxy methyl (serine), etc.'

The NCERT Chemistry text explains, 'This behaviour [behaving like salts] is due to the presence of both acidic (carboxyl group) and basic (amino group) groups in the same molecule.'

The NCERT Chemistry text defines essential amino acids as 'those which cannot be synthesised in the body and must be obtained through diet.'

The NCERT Chemistry text (Table 10.2: Natural Amino Acids) shows the general structure: H2N - CH(R) - COOH or R - CH(NH2) - COOH. The Biology text also refers to them as substituted methanes with hydrogen, carboxyl, amino, and R groups on the $\alpha$-carbon.

Looking at Table 10.2 (Natural Amino Acids) in the NCERT Chemistry text, Phenylalanine (Phe F) has C6H5-CH2- as its characteristic feature of the side chain, which includes a benzene ring.

The NCERT Chemistry text states, 'Equal number of amino and carboxyl groups makes it neutral...'

The NCERT Chemistry text explains, 'In zwitter ionic form, amino acids show amphoteric behaviour as they react both with acids and bases.' This behavior arises from the presence of both acidic and basic groups.

The NCERT Biology text states, 'A fatty acid has a carboxyl group attached to an R group... Palmitic acid has 16 carbons including carboxyl carbon.' Therefore, the R group contains $16 - 1 = 15$ carbons.

As per the NCERT text, 'Lactose... is composed of b-D-galactose and b-D-glucose. The linkage is between C1 of galactose and C4 of glucose.'