Molecular Basis of Inheritance — Page 3 | NEET Biology

Q21

Uridine, present only in RNA is a nucleotide

A Pyrimidine

B Nucleoside

C Nucleotide

D Purine

Correct Answer

Option B

Solution

(b) The combination of pentose sugar with nitrogenous bases (purines or pyrimidines) is called nucleoside.

Examples are adenosine, guanosine, cytidine, thymidine and uridine.

Q22

Transformation was discovered by Frederick Griffith:

A Meselson and Stahl

B Hershey and Chase

C Griffith

D Watson and Crick

Correct Answer

Option C

Solution

(c) Frederick Griffith (in 1928), a British Medical officer described the phenomenon of bacterial transformation.

Q23

Which one of the following is not applicable to RNA?

A 5 phosphoryl and 3 hydroxyl ends

B Heterocyclic nitrogenous bases

C Chargaff rule

D Complementary base pairing

Correct Answer

Option C

Solution

(c) Chargaff rule is not applicable to RNA

Q24

Molecular basis of organ differentiation depends on the modulation in transcription by

A ribosome

B transcription factor

C anticodon

D RNA polymerase.

Correct Answer

Option B

Solution

(b) Transcription factors regulate gene expression during organ differentiation.

Q25

In negative operon system

A co-repressor binds to repressor

B co-repressor binds with repressor

C co-repressor binds with corepressor

D CAMP has negative effect on lac operon

Correct Answer

Option A

Solution

(a) In negative repressible operon, co-repressor binds to repressor to block operator.

Q26

Which form of RNA has a structure resembling clover leaf?

A rRNA

B hn RNA

C mRNA

D tRNA

Correct Answer

Option D

Solution

(d) tRNA has a cloverleaf secondary structure.

Q27

The two polynucleotide chains in DNA are

A discontinuous

B antiparallel

C semi-conservative

D parallel.

Correct Answer

Option B

Solution

(b) The two DNA strands are antiparallel — one 5->3 and the other 3->5.

Q28

During transcription, RNA polymerase holoenzyme binds to a gene promoter and assumes a saddle-like structure. What is its DNA-binding sequence?

A AATT

B CACC

C TATA

D TTAA

Correct Answer

Option C

Solution

(c) The TATA box is the promoter sequence where RNA polymerase binds.

Q29

Nucleotide arrangement in DNA can be seen by

A X-ray crystallography

B electron microscope

C ultracentrifuge

D light microscope

Correct Answer

Option A

Solution

(a) In 1953 Wilkins obtained very fine X-ray crystallographic pictures of DNA from which Watson and Crick developed the double helix model of DNA.

Q30

One gene-one enzyme relationship was established for the first time in

A Salmonella typhimurium

B Escherichia coli

C Diplococcus pneumoniae

D Neurospora crassa.

Correct Answer

Option D

Solution

(d) Beadle and Tatum established one gene-one enzyme hypothesis using Neurospora crassa.