Extra content for essays - Photosystem

Question 1

What is a photosystem?

Answer 1

A funnel shaped light harvesting cluster of photosynthetic pigments with accessory pigments and a primary pigment reaction centre

Question 2

Where are photosystems located?

Answer 2

Thylakoid membrane

Question 3

What are the accessory pigments?

Answer 3

Carotenoids - absorb blue light reflect yellow and orange light
Xanthophyll (yellow) and carotene (orange) are the main carotenoids

Question 4

What is the primary pigment reaction centre?

Answer 4

P700 chlorophyll in photosystem 1
P680 chlorophyll in photosystem 2

Question 5

What happens in cyclic photophosphorylation?

Answer 5

• Uses only photosystem 1
• excited electron passes to electron acceptor and back to chlorophyll

Question 6

Importance of cyclic photophosphorylation?

Answer 6

• Generates ATP which can be used in LIR or used in guard cells to bring in potassium ions lowering water potential so water moves in via osmosis and guard cells swell and open stomata