Prepare for NEET Biology Molecular Basis of Inheritance with MCQs & PYQs on NEET.GUIDE. Access free practice, previous year questions, and expert explanations of DNA replication and genetics.
Which experiment definitively proved that DNA, and not protein, is the genetic material?
Griffith's experiment with Streptococcus pneumoniae
Avery, MacLeod, and McCarty's experiment with bacterial transformation
Hershey-Chase experiment using bacteriophages
Meselson-Stahl experiment demonstrating semi-conservative replication
What was the key observation in the Hershey-Chase experiment that supported DNA as the genetic material?
Radioactive sulfur (S) was found inside the bacterial cells.
Radioactive phosphorus (P) was found inside the bacterial cells.
Both radioactive sulfur and phosphorus were found inside the bacterial cells.
Neither radioactive sulfur nor phosphorus were found inside the bacterial cells.
Which of the following is NOT a characteristic of a good genetic material?
Able to replicate accurately
Chemically and structurally stable
Must be easily degradable
Scope for slow changes (mutations)
What was the transforming principle identified by Avery, MacLeod, and McCarty?
Protein
RNA
DNA
Carbohydrates
Which enzyme was used by Avery, MacLeod and McCarty to prove that DNA is the genetic material?
RNase
Protease
DNase
Lipase
In the lac operon, the repressor protein binds to which region to prevent transcription?
Promoter
Operator
Structural genes
Regulator gene
Which molecule acts as an inducer in the lac operon?
Glucose
Lactose
Allolactose
Galactose
What is the role of cAMP in the regulation of the lac operon?
It binds to the repressor, inactivating it.
It binds to CAP, enhancing RNA polymerase binding to the promoter.
It inhibits the transport of lactose into the cell.
It directly binds to the operator, blocking transcription.
In the presence of both glucose and lactose, the lac operon will be:
Strongly expressed
Weakly expressed
Not expressed
Constitutively expressed
A mutation in the operator region of the lac operon prevents the repressor from binding. What is the likely outcome?
No expression of the lac operon genes
Constitutive expression of the lac operon genes
Normal regulation of the lac operon
Increased sensitivity to glucose
