Question

Bt cotton is not
(a) A GM plant
(b) Insect resistance
(c) A bacteria gene expressing system
(d) resistant to all pesticides

Answer 1

Hint: Genetic engineering is the introduction of a gene or a set of genes from one organism to the genome of other organisms. Bt cotton also bears a foreign gene taken from a distinct organism. This gene product has given an edge to Bt cotton over traditional cotton varieties.

Complete answer:
Through genetic engineering, it is possible to develop crops that are intrinsically resistant to insects. Bt cotton is one such genetically modified or GM crop. The gene of bacteria Bacillus thuringiensis which codes for this insecticidal toxic protein has been introduced in cotton plants so that if any insect attempts to eat it, they would be killed. This bacteria gene expressing system has endowed the cotton insect resistant but not pesticide-resistant.

Additional Information: Bacillus thuringiensis is the most widely applied species of bacteria used as a biocontrol agent with as many as three subspecies to control insect pests such as Lepidopteran( moth, butterfly), Coleopteran( beetle), and Dipteran (true flies). They produce protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein known as Bt toxin.
Bacillus thuringiensis (Bt) toxic protein exists as an inactive protoxin in intracellular crystalline bodies. Once they are ingested by an insect, the protoxin is converted into an active toxin due to the solubilization of crystals in the alkaline pH of the insect’s gut. The toxin binds to the surface of the insect’s midgut epithelial cells and perforates it. The formation of pores causes cell swelling, lysis, and eventually death of the insect.
So, the correct answer is ‘resistant to all pesticides.’

Note:
-In 1995, the Environmental Protection Agency approved the release of genetically engineered Bt crops such as cotton, potatoes, corn, and rice.
-One of the advantages of Bt toxin is its narrow range of the spectrum. As many other insecticides kill various beneficial insects which may be pollinators such as bees, Bt only targets an individual insect species.