281.

The main constituent of most natural fibres is :

• starch

• glycol

• cellulose

• caprolactum

The type of bond that is most important in maintaining secondary structure of a protein is :

• disulphide bridges

• hydrogen bonding within the backbone

• hydrogen bonding between R group

• salt bridges

Find the hydrolysis product when a phosphodiester bond of nucleotide breaks.

• 3-OH-deoxyribose-5-PO${}_4^{3-}$

• 5-OH-deoxyribose-3-PO${}_4^{3-}$

• 2-OH-deoxyribose-2-PO${}_4^{3-}$

• 4-OH-deoxyribose-2-PO${}_4^{3-}$

Find the hydrolysis product of maltose.

• $\mathrm{\alpha }$-D-glucose + $\mathrm{\alpha }$-D-glucose

• $\mathrm{\alpha }$-D-glucose + $\mathrm{\alpha }$-D-fructose

• $\mathrm{\alpha }$-D-glucose + $\mathrm{\alpha }$-D-galactose

• $\mathrm{\alpha }$-D-fructose + $\mathrm{\alpha }$-D-galactose

Assertion : $\mathrm{\beta }$-pleated sheet structure of protein shows maximum extension.

Reason : Intermolecular hydrogen bonding is present in them.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

Assertion : Fructose is a reducing sugar.

Reason : It has a ketonic group.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Glucose contains in addition to aldehyde group :

• one secondary - OH and four primary - OH groups

• one primary - OH and four secondary - OH groups

• two primary - OH and three secondary - OH groups

• three primary - OH and two secondary - OH groups

A distinctive and characteristic functional group of fats is :

• a peptide group

• an ester group

• an alcoholic group

• a ketonic group

Hydrolysis of lactose with dilute acid yields :

• D - glucose + D - glucose

• D - glucose + D - galactose

• D - glucose + D - fructose

• D - galactose + D - fructose

Proteins are :

• polypeptides with low molecular weights

• polypeptides with high molecular weights

• polymers of amides

• polymers of secondary amines