Explain with the help of one example how genetically modified plants can
(a) Reduce usage of chemical pesticides.
(b) Enhance nutritional value of food crops.

Explanation

Genetically modified plants can reduce the usage of chemical pesticides by introducing pest resistant plants.
e.g., There are several nematodes that parasitie, a wide variety of plants and animals including human beings. A nematode Melodiogyne incognita infects the roots of tobacco plants and caues a great reduction in yield. A novel strategy was adopted to prevent this infestation which was based on the process of RNA interference (RNAi).
using Agropbacterium vectors, nematode-specific genes were introduced into the host plant. the introduction of DNA was such that it produced both sence and antisense RNA in theh ost cells.
These two RNA s being complementary to each other formed a double strand ed RNA that initialted RNAi and thus, silenced the specific mRNA of the nematode. the consequence was that the parasite could not survive in a trasngenic host expressing specific interfering RNA.
(b) Genetically modified plants can enhance nutritional value of food crops
e.f. Golden rice developed at Swiss Federal institute of technology is an example of nutritionaly modified crop. it is rich in vitamin A (b-carotene). The rice grains are nutritionally modified crop it is rich in vitamin. It contains beta-carotene gene from dafodil plant and also from some bacteria Golden rice can prevent child blindness which is caused due to the deficiency of vitamin-A.