Plasmid MCQ Questions and Answers Pdf - YB Study

Plasmid MCQ Questions and Answers Pdf

 MCQ on Plasmid with Answers: 

  • The plasmid is a small circular DNA molecule. As the most commonly used and simplest carrier in genetic engineering, it must include three parts: genetic marker gene, replication region, and target gene.
  • Plasmids (English plasmids) are small DNA molecules that are physically isolated from chromosomes and capable of autonomous replication. 
  • Plasmids are mainly found in bacteria, as well as in some archaea and eukaryotes (fungi and higher plants). 
  • Most often, plasmids are double-stranded circular molecules.
  • Plasmids perform regulatory and coding functions. 
  • The plasmid is a double-stranded covalently closed circular DNA molecule that can naturally form a supercoiled structure, and the size of different plasmids is between 2kb and 300kb.
  • A plasmid can enter a cell of a host organism in several ways such as conjugation, transformation, transduction, etc.
  • Plasmids are not essential substances for bacterial growth and reproduction and can be lost by themselves or eliminated by manual treatment, such as high temperature, ultraviolet light, etc. The genetic information carried by the plasmid can give the host bacteria certain biological shapes, which is conducive to the survival of the bacteria under specific environmental conditions.
  • The functions of plasmids are it helps to transfer genetic material by conjugation, synthesis of proteins lethal to other bacteria, synthesize hemolysins, and enterotoxins, and synthesis of antigens that cause bacteria to adhere to cells in humans and animals.


MCQs on Plasmid:

1. What is plasmid called?

(a) Plasmids are known to be minor, circular molecules of DNA that can replicate independently, as they do not depend on the organism's chromosomal DNA for replication. 

(b) A plasmid is a small circular DNA molecule found in bacteria and some other microscopic organisms.

(c) Both a and b

(d) None of these

Answer: C


2. Which among the following are the smallest plasmid and an ideal cloning vector?

(a) ColE1

(b) RP4

(c) PUC8

(d) F

Answer: C


3. Which of the following gene helps in identifying transformed cells?

(a) plasmid

(b) selectable marker

(c) structural gene

(d) vector

Answer: B


4. Which is the most commonly used plasmid?

(a) pBR322

(b) F- Plasmid

(c) YAC

(d) BAC

Answer: A


5. Which of the following is not a type of plasmid?

a) F

b) R

c) Ti

d) T4

Answer: D


6. If the plasmid and the foreign DNA are cut by the same restriction endonuclease, recombinant DNA can be formed by joining both by__________

(a) Polymerase III

(b) EcoRI

(c) Ligase

(d) Taq polymerase

Answer: C


7. The number of molecules of an individual plasmid normally found in a single bacterial cell is known as?

(a) Conjugative ability

(b) Competency

(c) Replicative ability

(d) Copy number

Answer: D


8. How the plasmid clones can be screened?

(a) By selectable markers

(b) By bacterial resistance gene

(c) For restriction site

(d) By ARS sequence

Answer: A


9. Find the incorrect statement about plasmids

(a) they are circular

(b) they replicate independently

(c) they are transferrable

(d) they are single-stranded

Answer: D


10. How can conjugative and non-conjugative plasmids be differentiated?

(a) based on size

(b) Presence of antibiotic resistance

(c) Number of cloning and digestion sites

(d) Presence of transfer genes

Answer: D


11. How many restriction sites are present in a plasmid?

(a) 1

(b) 2

(c) 3

(d) More than 1

Answer: D


12. The DNA molecule used for integrating foreign genes for cloning is called

(a) vector

(b) carrier

(c) template

(d) transformer

Answer: A


13. Who were the scientists who discovered the plasmid pBR322?

(a) Rodriguez and Bolivar

(b) Joller smith

(c) Herbert Boyer

(d) Stanley Cohen and Joller smith

Answer: A


14. Which one of the following is correct for the plasmid pBR322 of E.coli.?

(a) ampR and tetR – antibiotic resistance genes

(b) Hind III and EcoRI – selectable markers

(c) rop – reduced osmotic pressure

(d) ori – original restriction enzyme

Answer: A


15. Which one of the following is the first engineered plasmid vector?

(a) pBR322

(b) pBR320

(c) pUC18

(d) pSC101

Answer: D


16. The Ti plasmid is found in

(a) Agrobacterium

(b) Yeast as a 2mm plasmid

(c) Rhizobium of the roots of leguminous plants

(d) Azotobacter

Answer: A


17. Replication of plasmid DNA other than initiation is controlled by

(a) bacterial gene

(b) mitochondrial gene

(c) plasmid DNA

(d) none of these

Answer: A


18. Antibiotics are used in genetic engineering. They are useful

(a) to keep the culture free of microbial infections

(b) to select healthy vectors

(c) to identify replication start sites

(d) as selectable markers

Answer: D


19. A single-stranded, radiolabelled molecule of nucleic acids is called

(a) plasmid

(b) vector

(c) probe

(d) selectable marker

Answer: C


20. What is incorrect about plasmid?

(a) Helps in reproduction

(b) Contains stress-resistant genes

(c) Serves as the transformation vehicle

(d) They are the genetic material of the bacteria

Answer: D 


21. A vector that can clone only a small DNA fragment is

(a) cosmid

(b) plasmid

(c) Yeast artificial chromosome

(d) Bacterial artificial chromosome

Answer: B


22. What is the expanded form of pBR in pBR322?

(a) Plasmid Boliver and Rodriguez

(b) Plasmid Baltimore and Rodriguez

(c) Plasmid bacterial recombination

(d) Plasmid bacterial replication

Answer: A


23. Which of the following is true for a plasmid?

(a) Contains an origin of replication

(b) Imparts a useful characteristic to the host bacterium

(c) Possesses one or more genes

(d) Replicates only when the host genome is undergoing replication

Answer: D

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