Exam 3: Light-dependent Reactions

Question 1

Where do high energy electrons get donated to in photosystem II?

Answer 1

Pheophytin

Question 2

Where do electrons get passed to after pheophytin?

Answer 2

PQ

Question 3

What is the flow of the ETC between PSII and PSI?

Answer 3

PQ –> Cytochrome complex –> Plastocyanin

Question 4

How do protons get pumped into the thylakoid?

Answer 4

They are pumped by using the energy released when electrons are transported down the ETC

Question 5

What happens to potential energy as electrons move down the ETC?

Answer 5

Decreases

Question 6

What wavelength of light does photosystem II absorb?

Answer 6

680

Question 7

What wavelength of light does photosystem I absorb?

Answer 7

700

Question 8

Which photosystem oxidizes water?

Answer 8

Photosystem II

Question 9

What is oxygenic photosynthesis?

Answer 9

The splitting of water by PSII to replace its electrons and form oxygen

Question 10

What is the formula for oxygenic photosynthesis?

Answer 10

2 H2O –> 4H+ + 4e- + O2

Question 11

How many photons are absorbed by P680 and P700?

Answer 11

4 EACH

Question 12

At PSI, where are electrons passed down to?

Answer 12

Ferredoxin

Question 13

What transfers electrons to NADP+

Answer 13

NADP+ reductase, forms NADPH

Question 14

Does NADPH have reducing or oxidizing power?

Answer 14

Reducing

Question 15

What type of pattern describes how PSII and PSI interact?

Answer 15

Z scheme/noncyclic electron flow

Question 16

How is ATP made?

Answer 16

Because there are lots of protons inside the thylakoid, ATP synthase produces ATP

Question 17

How can you increase ATP production?

Answer 17

Cyclic electron flow: PSI can transfer electrons to PSII via ferredoxin to PQ instead of reducing NADP+ => increases ATP production

Question 18

Why do cyclic and noncyclic electron flow coexist?

Answer 18

To produce additional ATP and meet the energy demand for manufacturing sugars from CO2

Question 19

What is the ratio of ATP to NADPH produced in normal conditions?

Answer 19

Equal

Question 20

What is the sequence for movement of electrons during light dependent reactions?

Answer 20

Water to P680 to P700 to NADP+