Bt Cotton MCQ - Practice Questions & Answers

Quick Facts

Insect Resistant Transgenic Plant - Bt Cotton is considered one of the most asked concept.
37 Questions around this concept.

Some of the characteristics of Bt cotton are:

long fibre and resistance to aphids

medium yield, long fiber and resistance to beetle pests

high yield and production of toxic protein crystals which kill dipteran pests

high yield and resistance to bollworms

Bt cotton variety that was developed by the introduction of the toxin gene of Bacillus thuringiensis (Bt) is resistant to :

Insect pests

Fungal diseases

Plant nematodes

Insect predators

Match List I with List II :

List I	List II
A. α-1 antitrypsin	I. Cotton bollworm
B. Cry IAb	II. ADA deficiency
C. Cry IAc	III. Emphysema
D Enzyme replacement therapy	IV Corn borer

Choose the correct answer from the options given below:

A-II, B-I, C-IV, D-III

A-III, B-I, C-II, D-IV

A-III, B-IV, C-I, D-II

A-II, B-IV, C-I, D-III

Match the following:

Column I	Column II
(a) Bt-cotton	(i) Gene therapy
(b) Adenosine deaminase deficiency	(ii) Cellular defence
(c) RNAi	(iii) Detection of HIV infection
(d) PCR	(iv) Bacillus thuringiensis

a	b	c	d
iv	i	ii	iii

(a) (iii) (b) (ii) c) (i) (d)(iv)

(a)(ii) (b)(iii) (c)(iv) (d)(i)

(a)(i) b)(ii) (c)(iii) (d)(iv)

Which of the following Bt crops is being grown in India by the farmers?

Soybean

Maize

Cotton

Brinjal

Insect Resistant Transgenic Plant - Bt Cotton

Some strains of Bacillus thuringiensis (Bt) produce proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).
B. thuringiensis forms protein crystals during a particular phase of their growth.
These crystals contain a toxic insecticidal protein.
The bacterium itself is not killed by the toxin because Bt toxin protein exists as inactive protoxins but once an insect ingests the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which solubilises the crystals.
The activated toxin binds to the surface of midgut epithelial cells and creates pores that cause cell swelling and lysis and eventually cause the death of the insect.
Specific Bt toxin genes were isolated from Bacillus thuringiensis and incorporated into several crop plants such as cotton.
The choice of genes depends upon the crop and the targeted pest, as most Bt toxins are insect-group specific.
The toxin is coded by a gene named cry.
There are a number of them, for example:
- the proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms,
- cryIAb controls corn borer.