Genetically modified organisms in agriculture — practice questions

Here is a step-by-step calculation to determine the financial benefit of using Bt maize in this scenario.

Step 1: Calculate total potential yield without any loss.

• Total Area = 50 hectares
• Yield per hectare = 10 tonnes
• Maximum potential yield = 50 ha × 10 tonnes/ha = 500 tonnes

Step 2: Calculate the yield and revenue for non-GM maize.

• Yield loss percentage = 20%
• Yield loss in tonnes = 500 tonnes × 0.20 = 100 tonnes
• Final yield for non-GM maize = 500 tonnes - 100 tonnes = 400 tonnes
• Revenue from non-GM maize = 400 tonnes × $200/tonne = $80,000

Step 3: Calculate the yield and revenue for Bt maize.

• Bt maize prevents 95% of the potential loss.
• Loss prevented = 100 tonnes × 0.95 = 95 tonnes
• Remaining loss with Bt maize = 100 tonnes - 95 tonnes = 5 tonnes
• Final yield for Bt maize = 500 tonnes - 5 tonnes = 495 tonnes
• Revenue from Bt maize = 495 tonnes × $200/tonne = $99,000

Step 4: Calculate the increase in revenue.

• Increase in revenue = Revenue from Bt maize - Revenue from non-GM maize
• Increase in revenue = $99,000 -$80,000 = $19,000$

Answer: The potential increase in revenue from planting Bt maize is **$19,000**.$

Here’s a structured approach to answering this common Paper 4 question:

Advantages of GM Crops (4-5 marks)

• Increased Yield: GM crops like Bt maize are engineered with a gene from Bacillus thuringiensis to produce a protein toxin that kills specific insect pests, reducing crop damage and increasing harvestable yield. Herbicide-tolerant crops (e.g., Roundup Ready soya) allow effective weed control without harming the crop, leading to better resource allocation for crop growth and higher yields.
• Improved Nutritional Value: Golden Rice is genetically modified to produce beta-carotene, a precursor to Vitamin A. This addresses widespread Vitamin A deficiency in populations reliant on rice as a staple, improving public health.
• Reduced Pesticide Use: Pest-resistant GM crops decrease the reliance on chemical pesticides, which is beneficial for the environment by protecting non-target organisms and reducing farmer exposure to harmful chemicals.
• Enhanced Stress Tolerance: Some GM crops are being developed to withstand drought, salinity, or disease, allowing cultivation in marginal lands and increasing global food production resilience.

Disadvantages of GM Crops (4-5 marks)

• Development of Resistance: Continuous use of GM crops with a single mechanism of resistance (e.g., Bt toxin) can lead to the evolution of resistant pest populations or herbicide-resistant weeds ('superweeds'), rendering the GM trait ineffective over time.
• Gene Flow: There is a risk of genetically engineered genes escaping into wild plant populations or conventional crops through pollen dispersal. This could lead to wild relatives gaining undesirable traits (e.g., herbicide resistance in weeds) or contaminating organic crops.
• Impact on Non-Target Organisms: Although highly specific, concerns exist that toxins from GM crops (e.g., Bt toxin) could potentially affect beneficial insects or other non-target organisms in the ecosystem.
• Reduced Biodiversity: Extensive planting of a few high-yielding GM varieties can lead to monocultures, reducing genetic diversity within crops and making them more vulnerable to new diseases or environmental stresses.
• Economic Dependency: Farmers often purchase patented GM seeds from specific corporations, which can lead to economic dependency and prevent them from saving seeds for subsequent seasons, potentially increasing costs.

Ethical Considerations (3-4 marks)

• Human Health: Long-term safety concerns regarding potential allergenicity or toxicity of novel proteins introduced into GM foods, although regulatory bodies often deem approved GM foods safe for consumption.
• Environmental Impact: Worries about irreversible changes to ecosystems, potential harm to soil microbes, and the overall balance of natural processes due to the introduction of GM crops.
• Socio-economic Justice: Debates about whether GM technology primarily benefits large agricultural corporations, potentially disadvantaging small-scale farmers in developing countries due to seed costs and patenting.
• Moral Objections: Some individuals and groups have moral or religious objections to altering the genetic makeup of organisms, viewing it as 'unnatural' or 'playing God'.