Biomolecules — Page 2 | JEE Chemistry

Q11

Which of the following will react with CHCl3 + alc. KOH?

A Adenine and thymine

B Thymine and proline

C Adenine and lysine

D Adenine and proline

Correct Answer

Option C

Solution

Adenine and lysine both have primary anline react with CHCl3 + alc. KOH.

Q12

What are the functional groups present in the structure of maltose?

A One acetal and one ketal

B One ketal and one hemiketal

C Two acetals

D One acetal and one hemiacetal

Correct Answer

Option D

Solution

Maltose contains one acetal and one hemiacetal.

Q13

The functional group, which is found in amino acid is

A -COOH group

B -NH2 group

C -CH3 group

D both (a) and (b)

Correct Answer

Option D

Solution

Amino acids contain $-$

N{H_2}

and $-$

COOH

groups

e.g

Q14

The reason for double helical structure of

DNA

is operation of

A dipole-dipole interaction

B hydrogen bonding

C electrostatic attractions

D van der Waals' forces

Correct Answer

Option B

Solution

DNA

consists of two polynucleotide chains, each chain forms a right handed spiral with ten bases in one turn of the spiral.

The two chains coil to double helix and run in opposite direction held together by hydrogen bonding.

Q15

Insulin production and its action in human body are responsible for the level of diabetes. This compound belongs to which of the following categories?

A A co- enzyme

B An antibiotic

C An enzyme

D A hormone

Correct Answer

Option D

Solution

Insulin is a proteinaceous hormone secreted by $\beta$ -cells by islet of Langerhans of pancreas in our body.

Q16

Two monomers in maltose are :

A

\alpha

-D-glucose and

\alpha

-D-galactose

B

\alpha

-D-glucose and

\alpha

-D-Fructose

C

\alpha

-D-glucose and

\alpha

-D-glucose

D

\alpha

-D-glucose and

\beta

-D-glucose

Correct Answer

Option C

Solution

Two monomers in maltose are $\alpha$ -D-glucose & $\alpha$ -D-glucose.

Q17

Which one among the following chemical tests is used to distinguish monosaccharide from disaccharide?

A Seliwanoff's test

B Iodine test

C Barfoed test

D Tollen's test

Correct Answer

Option C

Solution

Barford test is used for distinguish monosaccharide from disaccharide.

Q18

Sugar which does not give reddish brown precipitate with Fehling's reagent, is :

A Glucose

B Sucrose

C Lactose

D Maltose

Correct Answer

Option B

Solution

Sucrose do not contain hemiacetal group.

Hence it does not give test with Fehling solution.

While all other give positive test with Fehling solution

Q19

In both DNA and RNA, heterocyclic base and phosphate ester linkages are at-

A

C_5^{'}

and

C_2^{'}

respectively of the sugar molecule

B

C_2^{'}

and

C_5^{'}

respectively of the sugar molecule

C

C_1^{'}

and

C_5^{'}

respectively of the sugar molecule

D

C_5^{'}

and

C_1^{'}

respectively of the sugar molecule

Correct Answer

Option C

Solution

In

DNA

and

RNA

heterocyclic base and phosphate ester are at

{C_1}'

and

{C_5}'

respectively of the sugar molecule.

Q20

The term anomers of glucose refers to

A isomers of glucose that differ in configurations at carbons one and four (C-1 and C-4)

B a mixture of (D)-glucose and (L)-glucose

C enantiomers of glucose

D isomers of glucose that differ in configuration at carbon one (C-1)

Correct Answer

Option D

Solution

Cyclization of the open chain structure of

D

-

(+)

- glucose has created a new stereocenter at

{C_1}

which explains the existance of two cyclic forms of

D

-

(+)

- glucose, namely

\alpha -

and

\beta -

.

These two cyclic forms are diasteromers, such diasteromers which differ only in the configuration of chiral carbon developed on hemiacetal formation (it is

{C_1}

in glucose and

{C_2}

in fructose) are called anomers and the hemiacetal carbon (

{C_1}

or

{C_2}

) is called the anomeric carbon.