Photosythesis

• What is a limiting factor?

  The product needed which is in shortest supply and will therefore limit the rate.
• describe the process of the Calvin cycle.

  CO2 enters the leaf through the stomata and diffuses into the stream. CO2 combines with ribulose bisphossphate (RuBP), catalysed by rubisco.This produces 2 glycerate 3 phosphate which is unstable. the energy from hydrolysed ATP and H+ ions from the light dependant reaction is used to break GP down into triose phosphate.Some of the TP is then converted into organic compounds e.g. glucose and lipids. Five out of every 6 molecules of TP and hydrolysed ATP produced per cycle are used to recreate RuBP.
• What is chemiosmosis?

  The movement of ions down their concentration gradient.
• What is an ETC?

  Electron transport chain - electron carrier molecule that transfer electrons to eachother.
• Why can only certain wavelengths of light be used in photosynthesis?

  On certain wavelengths can be absorbed by the photosynthetic pigment.
• Why is the optimum temp for photosynthesis not 40 degrees?

  At temps higher than 25 the stomata start to close to avoid water loss, subsequently reducing the intake of CO2 which is needed for photosynthesis.
• What are accessory pigments/carotenoids?

  Pigments that surround the primary pigment (chlorophyll)
• Where does photolysis of water occur?

  The interior space (lumen) of the thylakoid in PS11
• Name the coenzyme used in photosynthesis?

  NADP
• What is a coenzyme

  A molecule that aids the function of an enzyme by transferring a chemical group from one molecule to another.
• What does P700 or P680 on a photosystem mean?

  The wavelength of light that can be absorbed.
• What photosynthetic pigments are contained in the thylakoid?

  Chlorophyll A, chlorophyll B, and carotene.
• What is RuBP?

  ribulose biphosphate.
• What is a hexose sugar?

  Monosaccharide with six carbon atoms in each molecule.
• What happens to the rate of photosynthesis if the temperature is below 10 degrees?

  The rate will slow as the enzymes become inactive.
• What are the three stages in the Calvin cycle?

  carbon fixation, reduction, regeneration.
• Where does the Calvin cycle occur?

  In the stroma of the chloroplast.
• Which photosystem does cyclic phosphorolyation occur?

  PS1
• Give an equation for the photolysis of water?

  H20 = 2H+ + 1/2O2 + 2E-
• Is carbon dioxide reduced or oxidised in carbon fixation?

  Reduced
• How are electrons replaced in cyclic photophosphorylation?

  Once they have passed through the ETC instead of being used to reduce NADP they travel back to PS11.
• Why can't the light independent reaction take place in the dark?

  It requires reduced NADP and ATP from the light dependant reaction.
• Which part of chloroplasts absorb light energy?

  Chlorophyll - photosynthetic pigment.
• What spectrum of light does chlorophyll absorb?

  blue/violet and red.
• What happens during the reduction phase of the Calvin cycle?

  Glycerate 3 phosphate is converted to triose phosphate by reduced NADP and ATP
• How does carbon dioxide enter the plant?

  Via the stomata.
• What is carbon fixation?

  The process of transferring the carbon into the cycle from CO2.
• Which enzyme is involved in carbon fixation?

  Rubisco
• How does NADP get reduced?

  Excited electrons from PS1 in non cyclic photophosphorolysation are transferred down the ETC and used alongside a H+ proton to reduce NADP.
• What are the two stages of photosynthesis?

  light dependent and light independent (Calvin cycle).
• What are grana/granum?

  Stacks of thylakoid.
• What do plants needed energy for?

  Photosynthesis DNA replication Active transport Cell division Protein synthesis
• Where does the light dependant reaction occur?

  The thylakoid membrane.
• How are granum adapted to their function?

  Large surface area to increase the amount of light that can be absorbed.
• Where does the light independent reaction take place?

  In the stroma.
• What is contained in the stroma?

  Starch grains Oil droplets DNA
• How does water enter the plant?

  By osmosis through the root hair cells, then up the transpiration stream through the xylem.
• How does glucose produced by the Calvin cycle move around the plant?

  Translocation through the xylem.
• What i the glucose used for in the plant?

  Respiration
• What does non-cyclic photophosphorylation produce?

  ATP, reduced NADP and O2