NEET MCQ on Lac Operon Quiz Questions

1. Lac operon is an example of

A only positive regulation B only negative regulation C both positive and negative regulation D sometimes positive sometimes negative

2. In the presence of lactose, how long does it take for the lac operon to be expressed?

A when lactose equals glucose concentration B when glucose is more than lactose concentration C as long as lactose is more than glucose concentration D as long as lactose is more than galactose concentration

3. Which of these acts as an inducer of the lac operon?

A Allolactose B Lactose C Galactose D Glucose

4. The sequence of the structural genes in the lac operon is

A lacA-lacZ-lacY B lacZ-lacY-lacA C lacZ-lacA-lacY D lacA-lacY-lacZ

5. Regulation of the lac operon can be envisioned as regulation of enzyme synthesis by its

A lactose B substrate C carbohydrates D all of the above

6. Lac Operon will be turned on when

A Lactose is less than glucose B Lactose is less in the medium C Lactose is more than glucose D Glucose is enough in the medium

7. In a cell as per the Operon Concept, the regulator gene governs the chemical reactions by

A Inhibiting the substrate in the reaction B Inhibiting migration of mRNA into cytoplasm C mRNA transcription inhibited D Enzyme-reaction inactivation

8. In Lac-operon, the gene product of LacA gene is

A Beta-galactoside permease B Beta-galactoside transacetylase C Beta-galactosidase D Beta-galactoside isomerase

9. This condition in lac operon facilitates the condition of lac genes being transcribed at high levels

A low glucose, high lactose B low glucose, low lactose C high glucose, high lactose D high glucose, low lactose

10. The correct option regarding the lac operon in Ecoli from the following is

A Lac operon is switched on in the absence of lactose B Lac repressor binds to the lac promoter C β-galactosidase is the only enzyme produced in large quantities when lac operon is turned on D lac operon messenger RNA is a polycistronic mRNA