B4

• Word equation for photosynthesis:

  carbon dioxide + water ---> glucose + oxygen
• Photosynthesis takes place in chloroplasts - they contain chlorophyll that absorb light
• Uses of glucose in plants:

  1. For respiration
  2. Making cellulose
  3. Making amino acids
  4. Stored as oils or fats
  5. Stored as starch
• Factors that affect the rate of photosynthesis:

  • Light intensity
  • Concentration of CO2
  • Temperature
• Limiting factors affect the rate of photosynthesis
• Inverse square law:

  light intensity ∝ 1/distance^2
• Respiration is the process of transferring energy from glucose, which goes on in every cell.
• All living things respire. It's how they transfer energy from their food to their cells.
• Uses of energy transferred by respiration:

  • To build up larger molecules from smaller ones
  • In animals, it's used to allow the muscles to contract
  • In mammals and birds, it helps to keep their body temperature regulated
• In cells, there are lots of chemical reactions happening all the time which are controlled by enzymes.
• Metabolism is all the chemical reactions in an organism.
• There are two types of respiration:

  • Aerobic
  • Anaerobic
• Aerobic respiration is respiration involving oxygen.
• Most of the reactions in aerobic respiration happen inside mitochondria.
• Word equation for aerobic respiration:

  glucose + oxygen ---> carbon dioxide + water
• Anerobic means without oxygen. It's the complete breakdown of glucose, making lactic acid.
• Word equation for anaerobic respiration (muscle cells):

  glucose ---> lactic acid
• Plant and yeast cells can respire without oxygen too, but they produce ethanol and carbon dioxide instead off lactic acid. This is called fermentation.
• Word equation for anaerobic respiration (plant and yeast cells):

  glucose ---> ethanol + carbon dioxide
• Exercise causes you to respire more.
• Anaerobic respiration leads to an oxygen debt.