SC F3 2.5

•  The Gas Exchange In Plants

  Definition

  The respiration/transpiration also applies to plants where oxygen is required by cell respiration and carbon dioxide is released into the air
• Opened Stoma

  • During the day, photosynthesis
  • Water enters the control cell through the process of osmosis causing the control cell to become fresh and curved
  • Oxygen permeates into the cells through the stoma
  • High carbon dioxide released by body cells diffuses out through the stoma

  
• Closed Stoma

  At night, photosynthesis does not apply

  Water exits the control cell via osmosis

  The guard cells become wrinkled and the stoma closes
• Contaminants

  • Smoke
  • Dust
  • Haze

  Effect

  • The smoke particles clog the stoma pores and the rate of photosynthesis is reduced
  • The haze prevents the penetration of sunlight and the rate of photosynthesis is reduced
• Contaminants

  • Toxic gases such as nitrogen and sulfur dioxide

  Effect

  • The gases dissolve in rainwater into acid rain
  • Acid rain makes acidic soils unsuitable for cultivation
• Ways to control pollution

  • Enforcement of laws such as jail sentence or fine
  • Awareness campaign through mass media
  • Cleaning campaign around housing areas
  • Formal education in educational institutions