+91-8527521718
Signup | Login
  • 1(current)
Q. No.
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): In a transcription unit, the activity of RNA polymerase at a given promoter is in turn regulated by interaction with accessory proteins. 
Reason (R): These regulatory proteins can act both positively (activators) and negatively (repressors). 
In the light of the above statements, choose the most appropriate answer from the options given below :
1. Both (A) and (R) are True but (R) is not the correct explanation of (A).
2. Both (A) and (R) are False.
3. Both (A) and (R) are True and (R) is the correct explanation of (A).
4. (A) is True but (R) is False.
Subtopic:  Gene Regulation: Lac Operon | Gene Regulation in Eukaryotes |
Level 3: 35%-60%
Hints
Identify the incorrect statement:
 
I: The operator region is adjacent to the promoter elements in most operons and in most cases the sequences of the operator bind a repressor protein. 
II: Each operon has its specific operator and specific repressor. 
 
1. Only I 2. Only II
3. Both I and II 4. Neither I nor II
Subtopic:  Gene Regulation: Lac Operon |
 50%
Level 3: 35%-60%
Hints
premium feature crown icon
Unlock IMPORTANT QUESTION
This question was bookmarked by 5 NEET 2025 toppers during their NEETprep journey. Get Target Batch to see this question.
✨ Perfect for quick revision & accuracy boost
Buy Target Batch
Access all premium questions instantly

The repressor of the lac operon is:

1. Lactose itself 2. A steroid
3. Synthesized constitutively 4. A product of structural gene
Subtopic:  Gene Regulation: Lac Operon |
 54%
Level 3: 35%-60%
Hints
advertisementadvertisement

Consider the following diagram showing the working of the lac operon in E.coli in the presence of an inducer and choose the correct statement from the ones given below:

1. A is the inducer and can be either lactose or cAMP.
2. B is the enzyme that will metabolize glucose, the preferred energy source.
3. Some amount of C will be present in the cell even if lactose is absent.
4. The absence of D will stop lactose from entering the cell.

Subtopic:  Gene Regulation: Lac Operon |
 56%
Level 3: 35%-60%
Hints
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Lactose is the inducer of the lac operon in E.coli.
Reason (R): Lactose is the inhibitor of the lac operon.
In the light of the above statements, choose the most appropriate answer from the options given below :
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are False.
3. Both (A) and (R) are True but (R) is not the correct explanation of (A).
4. (A) is True but (R) is False.
Subtopic:  Gene Regulation: Lac Operon |
 79%
Level 2: 60%+
Hints

The lac Y gene codes for permease, which increases the permeability of the cell to:

1. Glucose 2. Galactose
3. cAMP 4. β-galactosides

Subtopic:  Gene Regulation: Lac Operon |
 72%
Level 2: 60%+
Hints
advertisementadvertisement

A very low level of expression of the lac operon has to be present in the cell:

1. When lactose is present 2. When lactose is absent
3. When glucose is absent 4. All the time
Subtopic:  Gene Regulation: Lac Operon |
 64%
Level 2: 60%+
Hints

Consider the following statements:

I: In prokaryotes, control of the rate of transcriptional initiation is the predominant site for control of gene expression.
II: Regulation of lac operon by CAP is referred to as negative regulation.
III: The inducer of the lac operon is lactose.

Which of the above statements are true?

1. I and II only 2. I and III only
3. II and III only 4. I, II, and III
Subtopic:  Gene Regulation: Lac Operon |
 58%
Level 3: 35%-60%
Hints
Study the diagram of the lac operon given below and select the correct statements:
Statement I: This is the working of a lac operon in the absence of an inducer.
Statement II: Repressor binds to the operator region and allows RNA polymerase to transcribe the operon.
1. Only Statement I 
2. Only Statement II 
3. Both Statement I and Statement II 
4. Neither Statement I nor Statement II 
Subtopic:  Gene Regulation: Lac Operon |
 82%
Level 1: 80%+
Hints
advertisementadvertisement
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Regulation of lac operon by a repressor is referred to as negative regulation.
Reason (R): lac operon is under the control of positive regulation as well.
In the light of the above statements, choose the most appropriate answer from the options given below :
1. Both (A) and (R) are True but (R) is not the correct explanation of (A).
2. Both (A) and (R) are False.
3. Both (A) and (R) are True and (R) is the correct explanation of (A).
4. (A) is True but (R) is False.
Subtopic:  Gene Regulation: Lac Operon |
 84%
Level 1: 80%+
Hints
  • 1(current)
Q. No.

NEET Information

courses

Company

Botany Questions

Chemistry Questions

Physics Questions

Zoology Questions

© 2026 GoodEd Technologies Pvt. Ltd.