Ecosystems

• We call plants producers and animals consumers
• Photosynthesis takes place in chloroplasts in leaf cells
• Chlorophyll uses light from the sun
• Energy from the sun is needed to help turn CO2 and water into glucose and oxygen
• Carbon dioxide + water ~> glucose + oxygen
• Most leaves:

  • are green - they contain chlorophyll which absorbs light
  • are thin - to allow gasses to diffuse easily
  • have large surface area - to absorb as much light as they can
  • have veins - which contain xylem vessels to transport water and phloem tubes to transport sugars
• Plants photosynthesise more during the summer because there is more sun
• If plants are not getting enough sunlight or nutrients then their growth will be stunted
• The rate of photosynthesis depends on how bright it is, temperature and carbon dioxide levels.
• The palisade mesophyll layer has lots of chloroplasts because that’s where photosynthesis takes place
• the Palisade Mesophyll layer is near the surface because it needs sun in order to do photosynthesis
• The spongy mesophyll layer has lots of air spaces so that is can get full of carbon dioxide and perform photosynthesis with it
• to transfer the energy stored in food, glucose reacts with oxygen in a aprocess called anaerobic respiration
• glucose + oxygen ~> carbon dioxide + water(+energy)
• carbon dioxide + water ~> glucose + oxygen = PHOTOSYNTHESIS
• respiration happens inside every cell in the mitochondria
• glucose ~> lactic acid(+energy) = ANAEROBIC RESPIRATION
• plants use anaerobic respiration at night time because there isnt any sun
• fermentation is the process by which microorganisms respire anaerobically.

  instead of producing lactic acid, carbon dioxide and ethanol are produced.
• glucose ~> ethanol + carbon dioxide(+energy) = FERMENTATION
• a food chain shows which organism is eating what

  the arrows show the transfer of energy from one organism to the next
• producer - gets its energy from the sun i.e makes it's own food e.g. wheat
• primary consumer - eats producers e.g. mice
• secondary consumers - eats primary consumers e.g. cats
• tertiary consumers - eats secondary consumers e.g. fleas
• food webs show feeding relationships between lots of organisms
• each level of a food chain is known as a trophic level
• pyramids of numbers

  advantages:

  • easy to count
  • no organisms killed

  disadvantages:

  • ignores size of organisms
  • difficult to convert plant leaves to numbers
• pyramids of biomass

  advantages:

  • overcomes the problems of pyramids of numbers

  disadvantages:

  • only measures a small number of the population
  • need to measure the dried weight of an organism