exam style questions topic 6

• Adaptations of root hair cells

  • larger surface area to increase rate of transpiration
  • thin cell wall - to reduce distance water and mineral ions have to travel
• Explain how sugars and water are transported around the plant

  • xyloem - made from lignified dead cells which have hallow tubes allowing water to move around the plant from the root hair to the leaves by transpiration where water evaporates from the leaves
  • pholem - made from sieve cells which are long thin cells enabling the flow of sugars by having little cytoplasm allowing them to flow easily and carries sugar from the leaves to the rest of the plant via translocation
• How do plant harmones work as weed killers

  • auxins
  • stimulate growth in weedkiller so the weed killer grows too quickly
• Devise an experiment to check auxins are in the tip of the plant between two plants

  • cut the tip from one plant
  • measures the changes in growth between the plants
• uses of auxins gibeerlins and ethene

  ethene - fruit ripening as ethene is added to unripened fruits so can be sold

  gibberlings - stimulate germination in dormant plants,fruits and flowers, sprayed on flowers before polluniation to produce seedless fruits

  auxins - added to the end of cuttings to stimulate growth in roots and used in weedkillers by selectively targeting them
• how can the photometer bubble experiment looking at light intensity be improved

  • collecting bubbles using a gas stringe and measure volume of gas collected
  • repeat the experiment at each intensity of light and calculate and average/mean
• How to measure the effect of temperature on the rate of photosynthesis

  • use a water bath to monitor the temperture of the water
  • count the bubbles at each temperature
  • use a control variable such as the same amout of water
• how does temeprature increase rate of phtosynthesis

  • as the temeprature increases so does the rate of photosynthesis as more enzyme - subtract concentrations are formed
  • maximum rate of photosynthesis is the enzyemes Optum temperture
  • past Optum bonds in active site break leading it to become denatured
• investigate rate of photosynthesis on plant (pratical)

  • light source away from plant
  • count the amount of bubbles produced in aq set time
  • repeat with different light intensities
• things that should be kept constant during light pratucal

  • temperature of water - use a heat shield
  • other external sources of light not from light meter (dark room)
  • volume of water
  • amount of carbon dioxide in water
• why is sodium hydrocarbonate added to the photosynthesis light pratical

  • to make sure the plant has enough carbon dioxide as it releases c02 into the solution
• how does d02 diffuse into the leaf

  • through diffusion in the stomota as it goes from an area of high concentration to an area of low concentration
• How can you identify that temperature is a limiting factor

  • keep light intensity the same
  • count number of bubbles
  • control the amount of c02