31 Year NEET Previous Year Questions: Biomolecules - NEET MCQ

We know that cellulose (C6H12O6 )n is the
chief constituent of cell walls of plants. It is
the most abundant organic substance found
in nature. It is a polymer of glucose with
3500 repeat units in a chain.

Enzymes are made up of protein with specific
structure.

All proteins are not found in L-form but they
may be present in form of D or L

It is a common pathway for both the aerobic
& anaerobic respiration in which 1 glucose
molecule is converted to 2 molecules of
pyruvate.

Phospholipids are derivatives of glycerol in
which two of the hydroxyl groups are
esterified with fatty acids while the third is
esterified with some derivative of phosphoric
acid with some alcohol such as choline,
ethanolamine, serine or inositol.

Amount of A = T and that of G = C.

The correct answer is Option C.
A peptide chain must have alternate C=O and NH groups from the peptide linkages. This is seen only in option C.

The bond formed between two amino acids
by the elimination of a water molecule is
called a peptide linkage or bond. The peptide
bond is simply another name for amide bond.

The product formed by linking amino acid
molecules through peptide linkages. —
CO—NH—, is called a peptide

Insulin helps in converting glucose to
glycogen

Triglycerides are lipids, hence these are
hydrolysed by lipases to glycerol and fatty
acids.

Haemoglobin acts as an oxygen carrier in
the blood since it reacts with oxygen to form
unstable oxyhaemoglobin which easily
breaks to give back haemoglobin and
oxygen.

The α-helix structure is formed when the
chain of α-amino acids coils as a right
handed screw (called α-helix) because of the
formation of hydrogen bonds between
amide groups of the same peptide chain, i.e.,
NH group in one unit is linked to carbonyl
oxygen of the third unit by hydrogen
bonding. This hydrogen bonding between
different units is responsible for holding
helix in a position.

Cell membranes (Plasma membranes) constitutes bilayer of phospholipid with embedded proteins. In humans, lipids accounts for upto 79% of cell membrance.

Testorterone and Adrenaline are steroid
harmone, Thyroxin is non-steroided harmone
glucagon is peptide harmone.

Vitamins are organic substances which does
not provide energy but are essential for
healthy growth and proper functioning of
body. Vitamins are not synthesized inside
human body but they are essential part of
our diet.

Pepsin and Trypsin are two enzymes
involved in the process (hydrolysis of
proteins)

Each nucleic acid consists of a pentose
sugar a heterocyclic base, and phosphoric
acid. The sugar present in DNA is 2-deoxy
-D (–) ribose and the sugar present in RNA
is D (–)- ribose. The chirality of DNA and
RNA molecules are due to the presence of
sugar components.

Thyroxine is an amino hormone.

In DNA the complimentary base are
Adenine and thymine.
Guanine and cytosine
The genetic information for cell is contained
in the sequence of bases A, T, G and C in
DNA molecule.

The DNA sequence that codes for a specific
protein is called a Gene and thus every
protein in a cell has a corrosponding gene.

Thyroxine is the only hormone among the
given choices that contains iodine. Its
structure is as follows:

Sucrose does not have free — CHO or
CO group, hence it does not undergo
mutarotation.

The correct answer is Option A.

Fructose reduces Tollen's reagent due to enolisation of fructose followed by conversion to aldehyde by base.
 
Only aldehydes reduce Tollen's reagent. But fructose is a ketone.
 
In aqueous solution, fructose is enolised and then converted into aldehyde in basic medium. 
 
All aldehydes generally reduce Tollen's reagent, thus fructose also reduces Tollen's reagent.
 

When the proteins are subjected to the
action of heat, mineral acids or alkali, the
water soluble form of globular protein
changes to water insoluble fibrous protein.
This is called denaturation of proteins.
During denaturation secondary and tertiary
structures of protein destroyed but primary
structures remains intact.

Enzymes are most reactive at optimum
temperature. The optimum temperature for
enzyme activity lies between 40°C to 60°C.

Beri-Beri.

Sucrose is a disaccharide of α–DGlucopyranose
and β–D-Fructofuranose.

The base pairs of the two strands of DNA
are linked together through H-bonds.