Bioenergetics

• Why is photosynthesis endothermic?

  • as energy is transferred from the environment to chloroplasts by light
• explain the different roles for the reactants and products in photosynthesis?

  Carbon Dioxide:

  • diffuses into the leaf through the stomata

  Water:

  • taken up by the roots and transported through the xylem to the leaves

  Glucose:

  • Used to make substances needed by the plant used in respiration to release energy

  Oxygen:

  • diffuses out of the leaf through the stomata
• why are plants producers?

  • they convert light energy into chemical energy
• what are the limiting factors of photosynthesis?

  • temperature
  • light intensity
  • carbon dioxide
  • amount of chlorophyl
• how does temperature affect photosynthesis?

  • Increasing temperature increases the kinetic energy of particles, more collisions between reactants and enzymes which results in the formation of products
  • At higher temperatures, enzymes that control the processes of photosynthesis can be denatured
  • affects the speed at which carbon dioxide and water move through a plant
• how does light affect photosynthesis?

  •  more light a plant receives, the faster the rate of photosynthesis
  • This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further
• How does Carbon Dioxide affect photosynthesis?

  • the more carbon dioxide that is present, the faster the reaction can occur
  • This trend will continue until some other factor required for photosynthesis prevents the rate from increasing 
• how does chloroplasts affect photosynthesis?

  • The more chloroplasts a plant has, the faster the rate of photosynthesis
  • as it contains a substance called chlorophyll which absorbs light for photosynthesis
• the amount of chlorophyll is affected by:

  • diseases (such as tobacco mosaic virus)
  • lack of nutrients (such as magnesium)
  • loss of leaves (fewer leaves means fewer chloroplasts)
• uses of glucose from photosynthesis:

  • Used for respiration for aerobic and anaerobic
  • Used to produce cellulose, which strengthens the cell wall
  • Combined with nitrate ions absorbed from the soil to produce amino acids for protein synthesis
• growing plants in a greenhouse means that:

  • control as many of the limiting factors of photosynthesis as possible
  • but the increased yield of the crop and fact that the crop can be harvested more frequently, means that the farmer will make more money
  • The levels of heat, light, water, carbon dioxide and nutrients are carefully controlled so only the smallest amounts needed are used so that farmers are not wasting money