The importance of limiting factors – Higher

• What process do plants use to make their own food?

  Photosynthesis
• Why is the food produced by plants important?

  It is important for the plants themselves and for other organisms that feed on them
• What are the limiting factors of photosynthesis?

  • Light intensity
  • Carbon dioxide concentration
  • Water availability
  • Temperature
• How do limiting factors affect crop yields?

  They reduce yields of crops and other economically-important plants
• How can increasing light intensity in greenhouses affect plant growth?

  It will increase the growth of crop or horticultural plants
• What materials can be used to construct greenhouses for maximum light transmission?

  Glass or alternative materials
• What is the purpose of artificial lighting systems in greenhouses?

  To provide optimum wavelengths of light for photosynthesis
• What is the typical concentration of carbon dioxide in greenhouses?

  About 0.1 percent
• What happens to carbon dioxide levels above 1 percent in greenhouses?

  It changes cell pH and can become toxic
• How can plant growers increase carbon dioxide concentration in a growing area?

  By using paraffin heaters or carbon dioxide wastes from industrial processes
• What is the role of fungi in greenhouses regarding carbon dioxide?

  They add carbon dioxide through their respiration
• What is the effect of high humidity in greenhouses?

  It promotes the growth of pathogenic fungi
• What is hydroponics?

  A system that involves growing plants in a porous material with nutrient-rich water
• Why is temperature regulation important in greenhouses?

  It increases the rate of photosynthesis and may require cooling
• How does increased temperature in greenhouses affect photosynthesis?

  It increases the rate of photosynthesis
• What are the methods used to manage limiting factors in photosynthesis for crop production?

  • Increase light intensity using greenhouses and artificial lighting
  • Enrich carbon dioxide levels using heaters and industrial waste
  • Maintain optimal humidity and temperature
  • Use irrigation systems and hydroponics for water and nutrients