Case Study:

In the cotton-growing region of Vidarbha in Maharashtra, farmers have historically struggled with pest attacks, especially from the cotton bollworm (Helicoverpa armigera). Frequent pesticide spraying increased farming costs and caused environmental pollution. To address this problem, scientists introduced Bt cotton, a genetically modified crop developed using biotechnology.

Bt cotton contains a gene derived from the soil bacterium Bacillus thuringiensis (Bt). This gene enables the cotton plant to produce a Cry protein toxin, which specifically targets and kills bollworm larvae when they feed on the plant. 

India approved the commercial cultivation of Bt cotton in 2002, marking a major milestone in agricultural biotechnology. Since then, Bt cotton has become widely adopted by farmers across several states including Maharashtra, Gujarat, and Punjab.

The introduction of Bt cotton significantly reduced the need for chemical pesticides. Studies show that insecticide use against bollworms decreased by 40-60%, while crop yields improved due to better pest resistance. 

However, biotechnology in agriculture also presents challenges. Over time, some pests such as the pink bollworm have developed resistance to Bt toxins in certain regions, requiring integrated pest management strategies. 

Scientists and policymakers emphasize the need for responsible biotechnology use, including crop rotation, refuge strategies, and continuous monitoring of pest populations. When applied carefully, biotechnology can improve food security, increase farm productivity, and support sustainable agriculture in India.

This case highlights how genetic engineering, ecological balance, and agricultural practices interact to shape the future of farming.

Questions

Section A - MCQs

1. Bt cotton protects crops mainly by producing:

A. A protein toxic to bollworm larvae
B. Extra chlorophyll for photosynthesis
C. Additional fertilizers within the plant
D. More seeds for reproduction

2. The Bt gene used in genetically modified crops is obtained from:

A. A virus
B. A bacterium
C. A fungus
D. An insect

3. The major advantage of Bt cotton cultivation for farmers is:

A. Increased use of fertilizers
B. Reduced pesticide requirement
C. Decreased plant growth
D. Elimination of irrigation

4. Development of pest resistance to Bt crops occurs mainly because:

A. Pests evolve genetic resistance over time
B. Farmers stop using fertilizers
C. Crops stop producing proteins
D. Sunlight destroys the Bt gene

Section B - Short Answer Questions

1. Explain how Bt toxin protects plants from insect pests.

2. Why is biotechnology considered important for sustainable agriculture?

3. What is meant by transgenic crops? Give one example used in agriculture.

Section C - Long Answer Question

1. Farmers in a region adopt Bt cotton to control pest infestation.

a) Explain how genetic engineering is used to develop Bt cotton.
b) Describe two advantages of using biotechnology in agriculture.
c) Discuss one ecological concern related to large-scale cultivation of genetically modified crops.

Answer Key

MCQ Answers

1. A - Bt cotton produces a toxin harmful to bollworm larvae.
2. B - The Bt gene originates from the bacterium Bacillus thuringiensis.
3. B - Bt cotton reduces the need for chemical pesticides.
4. A - Pests may evolve resistance through natural selection.

Short Answer Solutions

1. Bt toxin proteins produced by the plant enter the insect gut when pests feed on the plant. The toxin damages the gut lining of larvae, causing paralysis and death.

2. Biotechnology improves crop yield, enhances pest resistance, reduces pesticide use, and helps develop stress-tolerant crops, contributing to sustainable agriculture.

3. Transgenic crops are plants genetically modified by inserting genes from another organism using recombinant DNA technology. Example: Bt cotton.

Long Answer Solution

a) Development of Bt cotton

• Scientists isolate the Bt gene from Bacillus thuringiensis.
• The gene coding for Cry protein is inserted into cotton plant DNA using recombinant DNA technology.
• The plant expresses the toxin protein that kills specific insect pests.

b) Advantages

• Reduced pesticide usage
• Higher crop yield and improved farmer income

c) Ecological concern

Continuous exposure to Bt toxin may cause pests to develop resistance, reducing the effectiveness of the technology and affecting ecosystem balance.