The presence of _______ at the place of uracil also confers additional stability to DNA.

[Molecular-Basis-of-Inheritance] [class-xii ]

• Adenine
• Guanine
• Thymine
• Cytosine
Correct Option: C  [ Thymine ]

Remark: Thymine (5-methyl uracil) is more stable than Uracil.

Both DNA and RNA are able to _______

[Molecular-Basis-of-Inheritance] [class-xii ]

• Mutate
• Replicate
• Express
• All of these
Correct Option: D  [ All of these ]

Remark: Both can replicate, mutate, and express genetic information.

RNA can directly code for the synthesis of _______

[Molecular-Basis-of-Inheritance] [class-xii ]

• DNA
• Proteins
• Lipids
• Carbohydrates
Correct Option: B  [ Proteins ]

Remark: RNA (mRNA) directly codes for protein synthesis.

DNA is dependent on _______ for synthesis of proteins.

[Molecular-Basis-of-Inheritance] [class-xii ]

• DNA
• RNA
• Enzymes
• Lipids
Correct Option: B  [ RNA ]

Remark: DNA requires RNA as an intermediate to synthesize proteins.

Watson and Crick proposed the _______ scheme of replication of DNA.

[Molecular-Basis-of-Inheritance] [class-xii ]

• Conservative
• Dispersive
• Semi-conservative
• Non-conservative
Correct Option: C  [ Semi-conservative ]

Remark: The model suggests each new DNA molecule has one old and one new strand.

The experimental proof for semi-conservative replication was first shown in _______

[Molecular-Basis-of-Inheritance] [class-xii ]

• Fungi
• Plants
• Bacterium
• Animals
Correct Option: C  [ Bacterium ]

Remark: It was first shown in E. coli by Meselson and Stahl.

Meselson and Stahl used the heavy isotope _______ in their experiment.

[Molecular-Basis-of-Inheritance] [class-xii ]

• 14N
• 15N
• 32P
• 35S
Correct Option: B  [ 15N ]

Remark: They used 15N (heavy nitrogen) to distinguish DNA densities.

The heavy DNA molecule could be distinguished from the normal DNA by centrifugation in a _______ density gradient.

[Molecular-Basis-of-Inheritance] [class-xii ]

• Sucrose
• Cesium chloride
• Alcohol
• Water
Correct Option: B  [ Cesium chloride ]

Remark: CsCl density gradient centrifugation separates molecules based on density.

Taylor and colleagues used radioactive _______ to detect distribution of newly synthesized DNA in chromosomes.

[Molecular-Basis-of-Inheritance] [class-xii ]

• Adenine
• Thymidine
• Uracil
• Guanine
Correct Option: B  [ Thymidine ]

Remark: Taylor used tritiated thymidine in Vicia faba.

The main enzyme for DNA replication is DNA-dependent _______

[Molecular-Basis-of-Inheritance] [class-xii ]

• RNA polymerase
• DNA polymerase
• Ligase
• Helicase
Correct Option: B  [ DNA polymerase ]

Remark: DNA polymerase is the main polymerizing enzyme.