F214 Photosynthesis

State where the light dependent and light independent reaction take place.

Antwoord: Light dependent: on the thylakoid membrane Light independent: stroma

Name the main photosynthetic pigment in Photosystem I and II. Give two accessory pgiments.

Antwoord: Main: Chlorophyll a Accessory: Chlorophyll b/carotene/xanthophyll

What is the final hydrogen/electron acceptor in the light dependent reaction?

Antwoord: NADP

How many NADPH and ATP are created from the non-cyclic light dependent reaction?

Antwoord: 12 of each

How many ATP is needed for the light independent reaction? Outline how this is achieved?

Antwoord: 18 ATP are needed. Non-cyclic light dependent creates 12. 6 more are created by cyclic. The electrons in photosystem 1 and ferodoxin flit between each other, to maintain an electrochemical gradient, for more chemiosmosis to occur, for more H+ ions to drive the ATPase head and produce more ATP.

What is a photosynthetic pigment?

Antwoord: Molecules that absorb light energy, from a range of wavelengths in visible regions and has own distinct peak of absorption. Other wavelengths are reflected.

At what wavelength does Chlorophyll a absorb light?

Antwoord: In photosystem 2 - P680 nanometres In photosystem 1 - P700 nanometres

What is photolysis of water? Explain it\'s importance.

Antwoord: Water hydrolysed to hydrogen ions, oxygen and electrons. Hydrogen ions are forced out to the stroma (for chemiosmosis) Electrons replace those that are lost by chlorophyll a, in photosystem 2.

In the Calvin Cycle (light independent reaction), what catalyses the reaction between CO2 and Ribulose Bisphosphate (RuBP)? What do these reactants produce?

Antwoord: The enzyme Rubisco. GP is produced (Glycerate 3 Phosphate)

What happens to the rate of photosynthesis if the temperature increases?

Antwoord: High - more kinetic energy = higher rate of photosynthesis Too high - denatures proteins = very low rate of photosynthesis Higher than 25 degrees Celsius - Photo-respiration occurs (part photosynthesis, part respiration) Rubisco binds to oxygen, instead of carbon dioxide. This produces phosphoglycolate, which is toxic. So it needs to be broken down to GP or organic compounds. So this slows rate of photosynthesis.