Photosynthesis

• What are chloroplasts?


  Chloroplasts are small flattened organelles.
• What is the size range of chloroplasts?

  Chloroplasts are between 2 and 10 micrometres.
• What is the structure of the chloroplast's membrane?

  • Chloroplasts have a double membrane. The outer membrane is permeable to small substances while the inner membrane regulates the passage of larger substances.
• What fills the inside of chloroplasts?

  The inside of chloroplasts is filled with a gel-like fluid called stroma.
• What does the stroma contain?

  The stroma contains enzymes, starch granules, proteins, DNA, and ribosomes.
• What are thylakoids in chloroplasts?

  Thylakoids are disc-shaped sacs that contain pigments and enzymes.
• How are thylakoids organized within the chloroplast?

  The thylakoids are stacked into structures called grana and joined by the lamella.
• What are the structures called that pigments are arranged in?

  Photosystems
• What is the wavelength of light that Photosystem I absorbs best?

  700 nm
• What is the wavelength of light that Photosystem II absorbs best?

  680 nm
• Why do plants have several photosynthetic pigments other than chlorophyll?

  Because each pigment absorbs a different wavelength of light
• What are the main types of chlorophyll pigments?


  • Chlorophyll a (blue-green)
  • Chlorophyll b (yellow-green)
• What are carotenoids and their color range?

  • Carotenoids range in color from yellow to orange to red
• How does the number of double bonds in carotenoids affect their color?

  The more double bonds on the chain, the deeper the color
• Name two carotenoids and their colour.

  Carotenes - orange

  Xanthophylls - yellow
• What does the absorption spectrum show us?

  Chlorophyll absorbs the least amount of green light because it's reflected, making plants appear green.

  It absorbs the most blue and red light. 
• What is Engelmann's experiment?

  Engelmann passed white light into a prism to split the colours and used photosynthetic algae and oxygen dependant bacteria to show which colours most photosynthesis occurs.
• What is oxidation?


  Loss of electrons

  Loss of hydrogen

  Gain of oxygen
• What is reduction?


  Gain of electrons

  Gain of hydrogen

  Loss of oxygen
• What are the two stages of photosynthesis?

  Light Dependant Reaction

  Light Independent Reaction - Calvin Cycle
• What are the products of LDR and what are they used for?

  The LDR produces NADPH and ATP which is used for the Calvin Cycle
• Where does the light dependant reaction take place?

  The LDR takes place in the thylakoid membrane (space).
• Describe the light dependant reaction
• What is Photoionisation?


  this is when light is absorbed by the chlorophyll causing an electron to become "excited" and gain energy

  this causes the electron to be propelled outside the chlorophyll which oxidises the chlorophyll
• What happens at the Electron Transport Chain?

  the electrons from the chlorophyll are moved down the ETC through a series of redox reactions

  as they move down the etc the electrons release which are used to actively transport protons from the stroma into the thylakoid space to maintain the concentration gradient of protons
• What is Chemiosmosis?


  this is when protons diffuse back into the thylakoid space via the ATP synthase
• How is ATP formed in the LDR?

  when protons move through ATP synthase, it provides ATP synthase with energy to convert ADP+Pi into ATP
• How is NADPH formed in the LDR?

  electrons at the end of the electron transport chain and remaining protons are used to reduce NADP
• How are the electrons lost from the chlorophyll replaced?

  By photolysis, the splitting of water into hydrogen, electrons and oxygen
• What is Photolysis?

  Photolysis is the splitting of water into hydrogen, oxygen and electrons.

  hydrogen is released into the thylakoid space, oxygen diffuses out of the lead and electrons are used to replace missing electrons from the chlorophyll
• Where does the Calvin Cycle take place?

  Stroma
• what are the products of the Calvin cycle and what are they used for?

  the calvin cycle produced ADP+Pi and NADP which is used for the light dependant reactions
• Describe the Calvin Cycle
• What enzyme is used to combine RuBP and CO2?

  Rubisco
• What is formed when joining carbon and RuBP?

  2 molecules of GP
• How is GP converted into Triose Phosphate?


  ATP and NADPH is added to reduce GP into two Triose Phosphate moelcules
• What happens to the triose phoshate?

  5 out of the 6 molecules are used to regenerate RuBP

  1 out of the 6 molecules are converted into glucose and other organic molecules
• How many cycles need to take place to produce one hexose sugar?

  SIX
• What are the limiting factors of photosynthesis?

  Carbon dioxide concentration, light intensity and temperature
• How do farmers optimise conditions to improve growth?

  • increase CO2 concentration by using CO2 generators
  • increase light intensity by using lamps , and only using red/blue light
  • using greenhouses to keep the temperature optimum, heating and cooling systems