Question

Read the sources given and answer any four from the questions given below:

Agrobacterium tumefaciens is a plant pathogenic bacterium that can naturally transfer part of its plasmid DNA as it infects the host plant. The bacterium Agrobacterium contains large tumourinducing plasmids, Ti-plasmids and passes on this tumour-causing gene into the genome of the host plant. The host plant could be any dicotyledonous plant. Ti-plasmids are used as gene vectors to transfer foreign genes into target host cells. Vector-less methods involvethe transfer of gene, i.e., rDNA containing foreign gene by a direct method without any vector. These can be done by electroporation, microinjection and biolistic guns. In electroporation, temporary holes are produced in the plasma membrane of the host cell to facilitate the entry of foreign DNA. This is done by treating the bacterial cells with specific concentration of divalent cations like CaCl2. In microinjection foreign genes (rDNA) are introduced directly into the nucleus of plant or animal cells by using micropipettes. By using biolistic or gene particle gun, the microparticles of gold or tungsten particles coated with foreign DNA are bombarded into the target host cells with high velocity.

1. Agrobacterium is used as a vector because it
   1. infects dicot plants
   2. contains plasmid
   3. is easily available bacteria
   4. can transfer foreign gene into target host cell
2. Which of the following statements are true for T₁ plasmid?
   1. has a tumour-causing gene
   2. has foreign gene
   3. used in electroporation technique
   4. contains chromosomal DNA of bacteria
3. Microparticles of gold coated with rDNA are used in the following technique:
   1. electroporation
   2. biolistic gun
   3. microinjection
   4. T₁ plasmid
4. What is done in the electroporation technique?
   1. Cells are treated with divalent cations
   2. Temporary holes are created in the plasma membrane
   3. both (a) and (b)
   4. plasmids are used
5. rDNA are introduced directly into the nucleus of a plant by fine pipettes in the following technique:
   1. Agrobacterium
   2. microinjection
   3. electroporation
   4. gene particle gun

Answer 1

1. can transfer foreign gene into target host cell
2. has a tumour-causing gene
3. biolistic gun
4. both (a) and (b)
5. microinjection