This set of Class 12 Biology Chapter 11 Multiple Choice Questions & Answers (MCQs) focuses on “Tools of Recombinant DNA Technology: Cloning Vectors”.
1. Plasmids and ________ have the ability to replicate within bacterial cells independent of the control of chromosomal DNA.
Explanation: Plasmids and bacteriophages can replicate within bacterial cells without the help of chromosomal DNA. Thus they are self-replicating and autonomous in nature. They have their own replication machinery.
2. The sequence of DNA from where replication starts is called _______
a) selectable marker
b) origin of replication
c) ter sequence
d) genetic sequence
Explanation: The sequence of DNA from where the replication starts is called the origin of replication. It is also written as ‘ori’. It is also responsible for controlling the copy number of target DNA. Bacteria usually have only one origin of replication.
3. Viruses which infect bacteria are called ______
Explanation: Bacteriophages or simply phages are the viruses that infect bacteria. They are self-replicating in nature. Archaea is a domain of bacteria. pUC is a vector.
4. What helps in identifying the successful transformants?
c) Selectable markers
Explanation: A selectable marker is a gene that helps in identifying successful transformants. They eliminate the growth of non-transformants and favor the growth of the desired organism. It is one of the features which facilitate cloning in a vector.
5. Selectable markers are the genes which code for resistance to _______
d) foreign entity
Explanation: Genes coding for resistance to antibiotics are usually used as selectable markers. They are introduced in an organism especially bacteria along with plasmid. They help in the identification of transformants.
6. The process by which a foreign DNA is introduced into bacteria is called ______
Explanation: Transformation is a process in which a foreign DNA is directly picked up by the bacteria from the surrounding environment. It leads to a change in the characteristics of bacteria. It was first observed by Griffith in 1928.
7. ________ is an example of antibiotic.
b) Restriction endonuclease
Explanation: Antibiotics are the substances that either inhibit the growth or kill bacteria. They are widely used to treat diseases caused by bacteria. Some examples of antibiotics are kanamycin, ampicillin, penicillin, tetracycline, etc.
8. Insertion of recombinant DNA within the gene encoding for β–galactosidase leads to ________
c) insertional inactivation
Explanation: Insertional inactivation is the process in which the gene is inactivated due to the insertion of other genes within it or within its coding sequence. This leads to loss of function of that specific gene. Thus, insertion of recombinant DNA within the gene encoding for β–galactosidase will lead to insertional inactivation.
9. What may complicate the process of gene cloning within the cell?
a) One recognition site
b) Foreign DNA
c) More than one recognition site
Explanation: Recognition site is the sequence of DNA where the DNA is cleaved. The presence of more than one recognition site will lead to several cuts within DNA leading to fragmentation of DNA. This will complicate the process of gene cloning.
10. Which organism can transfer ‘T-DNA’ within plants?
a) Agrobacterium tumifaciens
c) Aspergillus niger
d) S. typhi
Explanation: Agrobacterium tumifaciens is the bacteria which transfers ‘T-DNA’ within plants. It mostly infects dicot plants. This ‘T-DNA’ is responsible for the formation of transformed cells called tumors from normal plant cells.
11. Which plasmid of Agrobacterium tumifaciens leads to tumor formation in dicots?
a) F plasmid
Explanation: The Ti plasmid in Agrobacterium tumifaciens leads to tumor formation in dicots. ‘Ti’ stands for tumor-inducing. It may contain more than one T-DNA region. This plasmid is modified and used as a cloning vector.
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