Photosynthesis

Question 1

What are the components of a chloroplast

Answer 1

Stroma. Granum. Inner membrane. Outer membrane. Thylakoid.

Question 2

What parts of the chloroplast do the light dependant and light independant occur?

Answer 2

Light dependant - Thylakoid membranes

Light independant - Stroma

Question 3

What pigments are responsible for photosynthesis and what colours does each absorb?

Answer 3

Chlorphyll a (blue-green)

Chlorophyll b (yellow-green)

Cartenoids (purple-green)

Question 4

What are the main potential limiting factors for photosynthesis?

Answer 4

• Light intensity
• CO2 levels
• Ambient temperature
• Water availability

Question 5

What’s the overall equation for photosynthesis?

Answer 5

6CO₂ + 6H₂0 → 60₂ + C₆H₁₂0₆

Question 6

What is the structure if ATP?

Answer 6

Question 7

Explain the light dependent reaction

Answer 7

• Photons hit chlorphyll in PS2
• Electron from chlorphyll is excited to high energy state and passed to an electron carrier
• Electrons lost due to excitation are replaced by photolysis of water. 4 photons to 2 electrons.
• Electrons are carried along electron transport chain in thylakoid membrane
• Increasing H+ concntration. H+, can only leave through ATPsynthase which bonds ADP and Pi
• Electrons are carried along ETC to PS1 to replace lost electrons from excitation
• Electron carriers take two electrons from PS1 and H+ reduces NADP+ to NADPH

Question 8

Explain the light independent reaction (Calvin cycle)

Answer 8

3CO₂ is added to 3RUBP (RUBISCO enzyme) to make a 6C compound. This compound is converted to 6GP (3C) (ATP → ADP). GP is converted to 6GALP (NADPH → NADP+). 1 GALP is lost to make cellulose and starch. 5 GALP go on to make 3 RUBP (ATP → ADP)