A.

Selectable marker

C.

gel electrophoresis

Gel electrophoresis is a technique to separate fragments of DNA. Since DNA fragments are negatively charged molecules they can be separated by forcing them to move towards the anode under an electric field through a medium/matrix. Now-a-days the most commonly used matrix is agarose which is a natural polymer extracted from seaweeds (e.g., Gelidium, Gracilaria, Gigartina, etc.).

A.

binds with epithelial cells of midgut of the insect pest ultimately killing it

Soil bacterium Bacillus thuringuensis (Bt) possesses is a gene family cry gene (1-40) over its plasmid, which forms endotoxic proteins, cry protein (protein crystals) during a particular phase of its growth. These crystals contain a toxic insecticidal protein.This toxin, however, does not kill the Bacillus.Actually, the BT toxin protein exists as an inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which solubilizes the crystals. The activated toxin binds to the surface of midgut epithelial and lysis, and eventually cause the death of the insect.

B.

Transformation of plant cells

In biolistic or gene gun method 1-2 g tungsten or gold particle (called microprojectile) coated with DNA to be used for transformation are accelerated to velocities which enable their entry into plant cells/nuclei. This technique has general applicability to plant species and can be used to deliver DNA into virtually all tissues.

B.

polymerase chain reaction

C.

electrophoresis

DNA fragments generated by the reaction is simply DNA replication in a test tube. Restriction mapping is the process of obtaining structural information on a piece of DNA by the use of restriction enzymes, e.g., endonucleases that recognise specific 4 to 8 base regions of DNA.