Photosynthesis

Question 1

Overall equation for photosynthesis. What is reduced and oxidized?

Answer 1

6CO2 + 6H2O + light energy –> C6H12O6 + 6O2
Water is oxidized to oxygen
carbon dioxide is reduced to glucose

Question 2

What is the photoelectric effect?

Answer 2

light energy excites electrons to a higher energy state with more potential energy

Question 3

What is the difference between chlorophyll a and b?

Answer 3

a - participates directly in light reactions
b - pigments called carotenoids protect leaves from wavelengths of harmful light and reflect green and yellow visible light

Question 4

Describe Photosystem 1.

Answer 4

chlorophyll is embedded in a light harvesting complex
light energy excites electrons and travel around the PS until they reach 2 chlorophyll molecules
e- then travel to primary e- acceptor that are replaced by lower energy e- to split water which produces O2 and protons
e- travel down transport chains to produce energy to pump H+ into thylakoid space
proton motive force is generated from water splitting and e- transport to allow the ATP synthase to produce ATP

Question 5

What is the Calvin Cycle?

Answer 5

the use of ATP and NADPH from light reactions to reduce CO2 and make sugars
Fixes CO2 into sugar precursors using e- from NADPH and energy from ATP
Light independent
regenerates NADP+ and ADP + Pi

Question 6

What is Phase 1?

Answer 6

Carbon Fixation
each 5C RuBP (Ribulose Biphosphate) is covalently bonded to a CO2
This is catalyzed by Ribulose Biphospate carboxylase/oxygenase (Rubisco)

Question 7

What is Phase 2?

Answer 7

Reduction
6C intermediate that splits into two and each 3C molecules acquires phosphate from 3ATP
6 3C compounds G3P are produced by reduction

Question 8

What is Phase 3?

Answer 8

Regeneration of CO2 acceptor (RuBP)

use of energy from ATP to take five G3P and rearrange them into 3 5C RuBP at beginning of cycle