In E. coli, the lac operon gets switched on when _______

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

• Lactose is present and it binds to the repressor
• Repressor binds to operator
• RNA polymerase binds to the operator
• Lactose is present and it binds to RNA polymerase
Correct Option: A  [ Lactose is present and it binds to the repressor ]

Remark: Lactose binding to repressor induces the operon.

A nucleosome is a portion of the chromonema containing _______

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

• Both DNA and histones
• Only histones
• Both DNA and RNA
• Only DNA
Correct Option: A  [ Both DNA and histones ]

Remark: Nucleosome = DNA + Histone octamer.

Which of the following is not a property of the genetic code?

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

• Non-overlapping
• Ambiguous
• Degenerate
• Universal
Correct Option: B  [ Ambiguous ]

Remark: The code is unambiguous.

Genes of interest can be selected from a genomic library by using _______

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

• Cloning vectors
• DNA probes
• Gene targets
• Restriction enzymes
Correct Option: B  [ DNA probes ]

Remark: Probes are used to screen libraries.

In an inducible operon, the genes are _______

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

• Usually not expressed unless a signal turns them "on"
• Always expressed
• Usually expressed unless a signal turns them "off"
• Never expressed
Correct Option: A  [ Usually not expressed unless a signal turns them "on" ]

Remark: Inducible operons are normally off.

The most abundant type of RNA in the cell is _______

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

• rRNA
• mRNA
• tRNA
• hnRNA
Correct Option: A  [ rRNA ]

Remark: rRNA is the most abundant.

The process of replication of DNA in E. coli requires an enzyme referred to as _______

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

• RNA dependent DNA polymerase
• RNA polymerase
• DNA dependent DNA polymerase
• DNA ligase
Correct Option: C  [ DNA dependent DNA polymerase ]

Remark: The main replicating enzyme.

DNA replication is a _______ process.

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

• Exergonic
• Endergonic
• Spontaneous
• Catalytic
Correct Option: B  [ Endergonic ]

Remark: It requires energy (dNTPs).

Which of the following figures correctly represents the replication fork formed during DNA replication?

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

• A
• B
• C
• D
Correct Option: D  [ D ]

Remark: Standard depiction of continuous/discontinuous synthesis.

A specific nucleotide sequence to which RNA polymerase attaches to initiate transcription of mRNA from a gene is _______

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

• Promoter
• Exon
• Intron
• Codon
Correct Option: A  [ Promoter ]

Remark: RNA Pol binds to the Promoter.