Bihar Board - Class 12 Biology - Chapter 11: Biotechnology: Principles and Processes Short Answer Question

Q.1. How is the copy number of plasmid vectors and yield of the recombinant protein related to each other?

A.1. The copy number of a plasmid vector is directly related to the yield of recombinant protein. Higher the copy number of vector plasmid, greater is the copy number of gene and consequently, the yield of the recombinant protein is in higher amounts.

Q.2. What are the features of a plasmid being used as a cloning vector?

A.2. The characteristics of plasmids being used as a cloning vector are:

• It should have an origin of replication

• It should have a selectable marker

• It should have restriction sites

Q.3. How is Ti plasmid of Agrobacterium tumefaciens modified to convert it into a cloning vector?

A.3. The Ti plasmid is a tumor-inducing plasmid. The genes responsible for its pathogenic nature are either removed or altered so that it does not harm the plants and only delivers the gene of interest.

Q.4. What is Biotechnology?

A.4. Biotechnology is defined as the broad area of biology which uses both the technology and the application of living organisms and their components to develop, modify and to produce a useful product for human welfare. The term ‘Biotechnology’ was coined in the year 1919 by an agricultural engineer Karoly Ereky, hence he is called as the father of Biotechnology.

Q.5. What is Genetic engineering?

A.5. Genetic engineering is the technique mainly used to change or to modify the genetic material (DNA/RNA), and to introduce them into other organisms.

Q.6.What are the  Principles of Biotechnology?

A.6.The modern biotechnology started with two crucial technologies:

1. Genetic engineering

2. Chemical engineering.

Q.7. What would happen if the restriction enzymes do not cut the DNA at specific recognition sequences?

A.7. If the restriction enzymes do not cut the DNA at the specific sites, the DNA fragment obtained will have no sticky ends, and hence, the construction of recombinant DNA would be difficult.

Q.8. How is DNA viewed on an agarose gel?

A.8. The DNA is stained with ethidium bromide which intercalates with the DNA strands and gives orange bands on exposure to ultraviolet light. Thus, one can view the DNA on an agarose gel.

Q.9. What would happen if a plasmid without a selectable marker was chosen as a cloning vector?

A.9. A selectable marker helps to distinguish transformed cells from the non-transformed ones. If the cloning vector does not have a selectable marker, it would be difficult to select the transformants.

Q.10. How are competent cells prepared by the action of CaCl2?

A.10. The divalent calcium ions create pores in the cell wall of the bacteria and facilitate the uptake of foreign DNA by the bacterial cell.

Q.11. A mixture of the fragmented DNA was run on an agarose gel. The gel was stained with ethidium bromide but no bands were observed. What would be the cause?

A.11. This may be due to the following reasons:

• The DNA must have degraded by nucleases.

• The electrodes are placed in the opposite direction in the gel assembly. Consequently, the DNA molecules move out of the gel.

• Maybe ethidium bromide was not added sufficiently and hence DNA was not visible.

Q.12. What is the role of Agrobacterium tumefaciens in plant transformation?

A.12. Agrobacterium tumefaciens is a plant pathogen that infects crops such as tomato, sunflower, cotton, soybean, etc. It causes crown gall disease in plants which are induced by Ti plasmid or the tumor-inducing plasmid. The Ti plasmid incorporates a DNA segment called the T-DNA into the DNA of the host plant cell. This T-DNA causes tumors.