Questions and answers for exam Preparation

MCQs

Total Questions : 89 | Page 3 of 9 pages

Question 21. M13-plasmid vectors are often used. Which of the following is not a feature for this?

They are known as phagemid, plage or phasmid
Replication takes place through the origin of replication of M13 derivatives only
Replication from M13 requires proteins to be provided by helper phage
Some of the examples of these types of the combination are pUC 118, 119 and 120

Discuss Question

Answer: Option B. -> Replication takes place through the origin of replication of M13 derivatives only
Answer: (b).Replication takes place through the origin of replication of M13 derivatives only

Question 22. The main advantage of phagemid is that it can be used for the generation of single or double stranded products without recloning.

True
False
May be True or False
Can't say

Discuss Question

Answer: Option A. -> True
Answer: (a).True

Question 23. Choose the correct statement for the infectious particle of lambda phage.

It is single stranded genome
It is circular double stranded genome
The ends are blunt with cos (cohesive) sequences
The ends are created by cleavage at cos sites during phage packaging

Discuss Question

Answer: Option D. -> The ends are created by cleavage at cos sites during phage packaging
Answer: (d).The ends are created by cleavage at cos sites during phage packaging

Question 24. Some changes are encountered in the infectious particle as it infects the cell. Choose the incorrect statement.

The infectious particle circularizes upon causing infection by annealing at cos sites
There are two promoters present, PR and PL
Upon infection only PR is activated
Promoters give rise to immediate early transcripts

Discuss Question

Answer: Option C. -> Upon infection only PR is activated
Answer: (c).Upon infection only PR is activated

Question 25. It is very important to study lambda biology as lambda phages are used for cloning purposes. Which of the statement is true for lambda phage?

It is an example of temperate phage
The fate of the phage is decided before it infects the cell
The lysis fate is that where the phage inserts its genome into the bacterial genome and the replication goes on
The lysogenic fate is that where the phage infects the cell and lysis is carried out

Discuss Question

Answer: Option A. -> It is an example of temperate phage
Answer: (a).It is an example of temperate phage

Question 26. Choose the correct statement for the cI gene.

It represses only cII gene
It activates cII gene and represses cIII gene
It represses both cII and cIII gene
It activates both cII and cIII gene

Discuss Question

Answer: Option C. -> It represses both cII and cIII gene
Answer: (c).It represses both cII and cIII gene

Question 27. Induction of lysogen takes place because of __________

Low levels of cII gene
Low level of cI gene
Low levels of both cI and cII gene
High levels of both cI and cII gene

Discuss Question

Answer: Option B. -> Low level of cI gene
Answer: (b).Low level of cI gene

Question 28. Choose the incorrect statement for cro and Q proteins.

They are required for the lytic life cycle to continue
Cro protein inactivates the PRM promoter
The Q protein is responsible for the expression of late genes
cII protein is required for the lytic life cycle to continue

Discuss Question

Answer: Option D. -> cII protein is required for the lytic life cycle to continue
Answer: (d).cII protein is required for the lytic life cycle to continue

Question 29. Which of the promoter requires a low level of cI gene for its activation?

Discuss Question

Answer: Option D. -> PRM
Answer: (d).PRM

Question 30. Choose the correct statement with respect to lysogen and prophage.

The integrated phage is called as lysogen
The infected bacterial cell is called a prophage
If there is only growth of few lysogens, the E. coli lawn would be turbid
If lysogens won’t be formed, the plaques won’t be clear

Discuss Question

Answer: Option C. -> If there is only growth of few lysogens, the E. coli lawn would be turbid
Answer: (c).If there is only growth of few lysogens, the E. coli lawn would be turbid