Question 1

Which of the following is not a pyrimidine base found in RNA?

Accepted Answer

Thymine is a pyrimidine base found typically in DNA, whereas RNA contains uracil instead of thymine along with cytosine.

Question 2

The length of DNA double helix in a typical mammalian cell is approximately:

Accepted Answer

A typical mammalian cell contains about 2.2 meters of DNA, calculated by multiplying the total number of base pairs (6.6 x 10^9) by the distance between two consecutive base pairs (0.34 nm).

Question 3

Who experimentally proved semi-conservative replication of DNA for the first time in E. coli?

Accepted Answer

Matthew Meselson and Franklin Stahl experimentally proved the semi-conservative mode of DNA replication in E. coli in 1958 using 15N heavy isotope and CsCl density gradient centrifugation.

Question 4

The enzyme responsible for transcription is:

Accepted Answer

RNA polymerase is the primary enzyme responsible for transcribing DNA into RNA during transcription.

Question 5

In lac operon, the repressor protein binds to which of the following?

Accepted Answer

The repressor protein binds to the operator region of the lac operon to block the transcription of structural genes in the absence of an inducer.

Molecular Basis of Inheritance — CBSE Class 12 Biology Important Questions & Revision Notes