Photosynthesis [Light reactions]

Question 1

Photo Overall reaction

Answer 1

6CO2 + 6H2O —> C6H12O2 + 6O2

Question 2

Light reactions overall reaction

Answer 2

2H2O + 2NADP —> 2H+O2 + NADPH2 + ATP

Question 3

3 steps for light reactions

Answer 3

1. Splitting of water
2. NADP+ reduction
3. Making H+ gradient for ATP

Question 4

Chlorophyll _ and _ are arranged in _ photosystems in ____ in the thylakoid membranes.

Answer 4

Chlorophyll a and b are arranged in PS1/2 photosystems in antennae in the thylakoid membranes.

Question 5

The thylakoid membranes are only permeable to ______

Answer 5

Mg and Cl ions

Question 6

Thylakoid membranes absorb best at ______ light. Chlorophyll _ absorbs at a higher value.

Answer 6

Blue or red

Chlorophyll a

Question 7

____ from light excite the ____.

Answer 7

Photons

Chlorophyll electrons

Question 8

Describe quantum tunneling.

What is the PS1 and 2 donors?

Answer 8

One electron is lost from a chlorophyll and passed to a receptor (turning it into chemical energy). Another chlorophyll accepts this from the donor to start the cycle again.

PS1 donor is water
PS2 donor is plastocyanin

Question 9

Describe cyclic electron flow

Answer 9

Photo excited electrons within PS1 can go this way. Only makes ATP.

Question 10

The chloroplast ATPase has more _____ then the mitochondria one, only uses the _______ so needs a high pH and ______ can move to balance it, which means the ____ needs to work harder.

Answer 10

The chloroplast ATPase has more subunits then the mitochondria one, only uses the chemical gradient so needs a high pH and Mg/Cl ions can move to balance it, which means the pump needs to work harder.

Question 11

Which parts of the thylakoid membranes have high and low H+ conc’s?

Answer 11

Stroma has low H+ conc

Thylakoid space has high H+ conc

Question 12

What happens at PS2?

H+ transferred:

Answer 12

Light hits, excited e- split water into 1/2O2 and 2H+. The electrons travel up to the primary electron acceptor then ultimately get passed to carrier Pq.

H+ transferred: 2 from water

Question 13

What happens at the cytochrome complex?

H+ transferred:

Answer 13

Electrons from Pq are passed through to carrier Pc.

H+ transferred: 4

Question 14

What happens at PS1?

H+ transferred:

Answer 14

Light hits, electrons are excited and passed to an electron acceptor then ultimately to carrier Fd

H+ transferred: none

Question 15

What happens at NAD+ reductase?

Answer 15

Electrons come from Fd and are used to make NADPH which then goes to the Calvin cycle.