plant structures and their functions

• photosynthesis is an endothermic reaction meaning its a chemical reaction hat absorbs energy from its surroundings causing the temperature of its surrounds to decrease.
• photosynethesis takes place inside the chloroplast in the chlorophyll.
• The word equation for photosynthesis is:

  carbon dioxide + water → glucouse + oxygen
• The balanced symbol equation for photosynthesis is:

  6CO2 + 6H2O → C6H12O6 + 6O2
• The glucouse produced by photosynthesis is used for:

  • cellular respiration
  • make cellulose (strengthen cell walls)
  • make starch (long term storage)
  • make amino acids
  • make oil and fats
• Factors affecting the rate of photosynthesis:

  • light intensity
  • temperature
  • carbon dioxide concentration
  • chlorophyll concentration
• levels of chlorophyll within a plant may vary due to:

  • disease
  • environmental stress
  • lack of nutrients
• Transpiration is the loss of water vapour from the parts of the plant that are above ground. Through evaporation.
• Things affecting the rate of transpiration:

  • light intensity
  • temperature
  • air flow
  • humidity
• Phloem cells transport sugars and amino acids up and down the plant.
• Phloem cells are made up of living cells arranged end to end.
• Phloem vessels contain cytoplasm and this goes through the holes in the sieve plates from one cell to the next.
• Xylem cells transport water and mineral ions from the roots to the leaves.
• Xylem cells are made of dead cells.
• Xylem don't have end walls so they form a continous hollow tube.
• Xylem cells are strengthened by a substance called lignin
• Root hair cells absorb water and mineral ions form the soil
• Root hair cells are adapted for the efficient uptake of water by osmosis and mineral ions by active transport.
• root hairs increase the surface area to volume ratio.
• guard cells control the opening and closing of stomata.