(a) State the role of DNA ligase in biotechnology.

(b) What happens when Meloidegyneincognitia consumes cells with RNAi gene?

(a) The role of DNA ligase in biotechnology is that it acts on cut DNA molecules and joins their ends.

(b) When Meloidogyne incognita which is a parasite, consumes cells with RNAi gene, it cannot survive thus preventing infestation. The introduced RNAi gene forms both sense and anti-sense RNA. Because these two strands are complementary to each other, they bend and form ds RNA, leading to RNAi. Thus, the mRNA of the parasite is silenced and the parasite is unable to survive.