Edexcel IGCSE Biology: Food Production Revision Notes

Crop Plants

Glasshouses & Polythene Tunnels

• Limiting Factors:
  • Affect rate of photosynthesis
  • Enclosed environments like glasshouses help control climate and improve yields
• Glasshouses:
  • Can manipulate conditions for increased photosynthesis
  • Use artificial heating, lighting, CO2 enrichment, and regular watering
  • Cost vs. income balance is necessary
• Polythene Tunnels (Polytunnels):
  • Protect crops from weather and pests
  • Slightly increase internal temperature

Increasing Carbon Dioxide & Temperature

• Limiting Factors of Photosynthesis: Temperature, light intensity, CO2 concentration
• Temperature:
  • Increases photosynthesis rate up to a point, after which enzymes denature
• Light Intensity & CO2 Concentration:
  • More light and CO2 increase photosynthesis rate until another factor becomes limiting

Fertilisers

• Role of Fertilisers:
  • Supply essential nutrients (N, P, K) to soil
  • Increase crop size and health, leading to better yields
• Types of Fertilisers:
  • Organic (manure, compost) and chemical (granules, sprays)

Pest Control

Chemical Control

• Pesticides:
  • Insecticides, herbicides, fungicides
• Advantages: Effective, immediate
• Disadvantages: Resistance, non-specific, bioaccumulation

Biological Control

• Use of Natural Predators:
  • E.g., ladybirds for aphids, parasitic wasps for whitefly
• Advantages: Long-lasting, no resistance, environmentally friendly
• Disadvantages: Slow, non-specific, may become pest

Yeast in Food Production

Bread Making

• Role of Yeast:
  • Breaks down starch, switches to anaerobic respiration
  • Produces CO2, causing dough to rise
  • Ethanol evaporates during baking

Anaerobic Respiration in Yeast

• Fermentation: Produces ethanol and CO2
• Investigation of Temperature Effect:
  • Use of yeast, sugar solution, oil layer, limewater, and water bath
  • CORMS approach for experimental design

Role of Bacteria in Yoghurt Production

Yoghurt Production Process

• Bacteria Used: Lactobacillus
• Process:
  • Sterilisation, pasteurisation, incubation
  • Lactose is converted to lactic acid, thickening milk

Industrial Fermenters

Usage and Control

• Purpose: Large-scale microorganism culture for various products
• Controlled Conditions:
  • Aseptic precautions, nutrient supply, temperature, pH, oxygenation, agitation

Fish Farming

Benefits and Methods

• Advantages:
  • Control over breeding, disease, water quality, and feeding
• Methods to Ensure High Yields:
  • Water filtering, predation control, antibiotics, waste management, feeding practices, selective breeding