Question

The crops having the cry-genes need
(A) no insecticide
(B) mild quantity of insecticide
(C) a large amount of insecticide
(D) 5 kg insecticide/hectare

Answer 1

Hint: In cry-genes cry stands for crystal, these are of many different types and are insect-specific that is each type of gene is effective only for a certain group of insects. These genes do not affect the organism from which it is extracted.

Step by step solution:
 The cry gene family is a sizable, still-expanding family of homologous genes that Bacillus thuringiensis produces during the late exponential phase of growth. Each gene in the cry gene family encodes a protein with strong specific action against just one or a few insect species. Cry IAB, Cry IAC, and Cry IIAB are different varieties of cry genes. Corn is guarded against borer pests by the cry gene IAB. The cotton plant-destroying behaviour of bollworms is controlled by the cry genes IAC and IIAB.
The cry gene produces the crystal protein known as cry, which is lethal to insects. It is created inactively by Bacillus thuringiensis bacteria. The insects' alkaline pH aids in the activation of cry proteins after consumption. As was previously noted, it is generally agreed that the main function of cry toxins is to lyse midgut epithelial cells of the target insect by creating apertures in the cell's apical microvilli membrane.
Cry genes are found in Bt crops, which do not require insecticide. Since Bacillus thuringiensis is a naturally occurring insecticide with biopesticidal qualities, it can be used to control pests in some circumstances.
So, option (A) is correct.
Note: Cry genes have been successfully incorporated into transgenic plants to manage caterpillars and are effective against lepidopteran insect pests. The use of Bt rice, however, could pose environmental dangers, just like other plant protection techniques.