NEET: Multiple Choice questions: Regulation of gene expression or lac operon

1. In Prokaryotes, Regulation of gene expression takes place at which of the following level

A. Replication level

B. Transcriptional level

C. Translational level 

D. Splicing level

Answer: B Explanation 

2. Consider the following level at which Regulation of gene expression takes place in Eukaryotes and select the correct code: 

1. Replication level

2. Transcriptional level

3. Translational level

4. Splicing level

5. Transport of mRNA from nucleus to cytoplasm 

A. 1,3,4 and 5 

B. 1,2,3,and 5

C. 2,3,4 and 5

D. 1,2,3 and 5

Answer: C Explanation 

3. Consider the following statement and select the number of correct statement:

1. Lactose is source of energy in E.Coli and play role to express the gene responsible for beta galactosidase enzyme.

2. Beta galactosidase is the responsible to catalyse the hydrolysis of a disaccharide lactose into glucose and galactose.

3. There are two types of regulation : Postive and negative 

4. Repressible and inducible regulation is also called as negative and postive regulation.

A. One             B. Two

C. Three           D.Four 

Answer: D Explanation 

4. Which of the following statement is correct for the regulation of gene expression in Prokaryotes.

A. In prokaryotes, Promoter region of transcription unit and RNA polymerase enzyme regulate gene expression.

B. The activity of RNA polymerase is regulated by interaction with the accessory protein.

C. The activity of promoter region is regulated by the interaction of protein with the DNA sequences.

D. All of the above 

Answer: D Explanation 

5.During gene regulation, the accessibility of promoter region is  regulated by the interaction of protein with the DNA sequences, called

A. Regulator     B. Repressor

C. Operator       D.structural

Answer: C Explanation

6.Which of the following statement is incorrect.

A. The accessibility of promoter regionin E.coli is depend on lactose, hence called lac operon.

B. lac operon in E.coli was demonstrated by Beadle and Tatum.

C. Each operon system has its specific operator and specific repressor region.

D. The operator region is located near  to the promoter region in E.Coli

Answer: B Explanation

7.  Who were the first to describe a gene regulatory system at the transcriptional level in E.coli.

A. Sutton and Boveri

B. Beadle and Tatum 

C. Jacob and Monad 

D. Wilkins and Franklin 

Answer : C Explanation

8. lac operon system of E.coli contain

A. 3 regulatory gene and 1 structural gene.

B. 3 regulatory gene and 3 structural gene.

C. 1 regulatory gene and 1 structural gene.

D. 1 regulatory gene and 3 structural gene.

Answer : D Explanation

9. Regulatory gene is denoted by the 

A. z      B. y     C. i     D. a

Answer : C Explanation

10. Structural gene is polycistronic and contain three gene , named

A. z,  y and a      B. A,B and O

C. B, C and D     D, hc, hb, ha 

Answer: A Explanation

11.  Match the list

( Gene)       ( Code for)

A. i        1. Beta galactosidase

B. z       2. Permease

C. y       3. Transacetylase

D. a      4. Repressor protein                                 

     A        B       C     D 

A.  1         2       3     4

B.  1         3       2     4

C.  4        1        3     2

D.  4        3       2      1

Answer: D Explanation

12. Which one of the following statement is not correct for the regulator gene in lac operon.

A. This gene transcribe repressor RNA and than repressor protein.

B. This gene remain active in E.coli until lactose is absent.

C. It is denoted by i  gene.

D. This gene form all enzyme required for metabolism of E.coli

Answer: D Explanation

12. Which one of the following statement is / are correct for Beta galactosidase. 

A. The z gene code Beta-galactosidase enzyme.

B. Beta-galactosidase enzyme increase permeability of bacterial cell wall.

C. Beta-galactosidase enzyme is the responsible for the hydrolysis of lactose into glucose and galactose.

D. All of the above.

Answer: D Explanation

13. Consider the following statement and select the correct code.

1. The permease enzyme  which increase the permeability of cell of E.coli.

2.The function of the transacylase enzyme is unknown so far. 

A. Only 1      

B. Only 2

C. Both 1 and 2

D. Neither 1 nor 2

Answer: C Explanation

14. Which one of the following is responsible for the switch on or off for operon system in E. Coli hence refer to inducer.

A. Lactose        B. Galactose

C. Maltose        D. Glucose

Answer: A Explanation

15. Arrange the following steps in sequential order if lactose is absent  or the  operon system is switch off in E.coli.

1. Formation of repressor mRNA from regulator gene

2. Formation of repressor protein .

3. Prevent  RNA polymerase to proceed transcription

4.  Repressor protein bind operator 

A. 4,3,2,1        B.1,2,3,4

C. 1,2,4,3        D.1,3,2,4

Answer: C Explanation

16. Which one of the following statement is not correct if lactose is present or operon is switched on.

A. Lactose bind the repressor protein so that repressor can not bind operator.

B. The structural  gene containing z, y,  a,  gene form lac mRNA through transcription.

C. All the protein beta-galactosidase, permease  and transacetylase are formed  by translation through lac mRNA.

D. lac mRNA is transcribed through RNA Polymerase when lactose is absent.

Answer: D Explanation

17. Consider the following statement and select the correct code.

1. Formation of repressor protein from regulator gene untill lactose is absent, called negative regulation.

2.The formation of beta-galactosidase,  permease  and transacetylase through lac mRNA due to presence of inducer ,called postive regulation 

A. Only 1      

B. Only 2

C. Both 1 and 2

D. Neither 1 nor 2

Answer: C Explanation

18. Study the following diagram and Match the list:

A : 1. Beta galactosidase 

B : 2. Transacetylase

C : 3. Permease 

D : 4. Repressor protein 

E : 5 . Repressor mRNA

        A  B  C  D  E

A.     2   1  3  5   4

B.     1   3  2  5   4

C.     1   2  3  5   4

D.     2   1  3  4   5

Answer: C Explanation