Photosynthesis

Question 1

what is photosynthesis?

Answer 1

converting light to chemical energy

Question 2

what are 5 things that require photosynthesis?

Answer 2

• atoshperic oxygen
• global carbon cycle
• food
• fuel
• medicine

Question 3

where does photosynthesis happen?

Answer 3

in the chloroplasts

Question 4

what are the 2 reactions in photosynthesis?

Answer 4

stage 1: light reactions
stage 2: dark reactions

Question 5

what are the 3 key components in the light reaction?

Answer 5

• pigments
• photosystems
• electron transport chain

Question 6

what is the function of the pigment in the light reaction?

Answer 6

Photosynthetic pigments absorb the light that powers photosynthesis

Question 7

what is chlorophyll a?

Answer 7

• Green pigments found in plants, algae and cyanobacteria
• Absorbs light that powers photosynthesis through the excitation of electrons located in the porphyrin-like ring
• Make up an antenna complex that is associated to a photochemical reaction centre, forming a photosystem

Question 8

what is the difference between chlorophyll a and b?

Answer 8

Chlorophyll b has the same structure as chlorophyll a but the CH3 is replaced by an aldehyde group (-CHO) and absorbs at 500 – 640 nm (appearing olive green)

Question 9

what are carotenoids?

Answer 9

• Carotenoids are yellow, orange, red or brown pigments
• Absorb strongly in the blue-violet range

Question 10

whhat is the function of carotenoids?

Answer 10

• Known as accessory pigments (along with chlorophyll b)
• Pass absorbed light energy to chlorophyll a
• Provide photoprotection

Question 11

once the pigment has absorbed the energy, what are the 3 possible fates of the energy?

Answer 11

• Converting extra energy to heat or to a combination of heat and light
• Transferring energy to a neighbouring chlorophyll molecule – resonance energy transfer
• Transferring from a negative charged high-energy electron to another nearby molecule (electron acceptor)

Question 12

what are the 4 steps to the photosystem?

Answer 12

1) reonance energy transfer
2) charge seperation
3) electron transfer
4) photolysis

Question 13

what is the electron transport chain?

Answer 13

Light energy drives the synthesis of both ATP and NADPH

Question 14

what is the equation of photolysis?

Answer 14

2H2O –> 4H+ + O2 + 4e-

Question 15

what is cyclic electron flow?

Answer 15

• To generate more ATP without making NADPH
• Switch photosystem I into cyclic mode also known as cyclic photophosphorylation

Question 16

what is the equation for the calvin-benson-bassham cycle?

Answer 16

6CO2 + 11H2O + 12 NADPH + 18 ATP –>
Fructose-6-phosphate + 12 NADP+ + 6H+ + 18 ADP + 17Pi