Gen. Bio. Quiz 2: Light-Dependent Reaction

Question 1

Light-dependent reactions
a. requires _________
b. occurs in the _____________
c. involves two _________ and an _________

Answer 1

a. sunlight
b. thylakoid membrane
c. photosystems; electron (e-) transport chain

Question 2

Large complexes of proteins and pigments (light absorbing molecules) that are optimized to harvest light.

Answer 2

Photosystems

Question 3

What are other names for photosystem I and photosystem II?

Answer 3

PSI: P700
PSII: P680 (functions first)

Question 4

4 main processes of light-dependent reaction:

Answer 4

1. Light absorption in PSII
2. ATP Synthesis
3. Light absorption in PSI
4. NADPH Formation

Question 5

What is the special pair of chlorophyll a molecule?

Answer 5

Reaction-center Complex/Chlorophyll

Question 6

Process.
a. Once photon is absorbed, energy is transferred from one pigment molecule to another until it
reaches the reaction center chlorophyll.

Answer 6

a. Resonance Energy Transfer

Question 7

Process.
b. Electron is elevated to an orbital (high PE), which makes it __________
c. Once excited, chlorophyll electron is _______ and cannot stay long.

Answer 7

b. excited
c. unstable

Question 8

Process.
d. Electron is now transferred to primary electron acceptor called ___________.

Answer 8

Pheophytin

Question 9

Process.
e. The electron will be passed on
through the first leg of the electron
transport chain in a series of
____________

Answer 9

e. redox (electron transfer) reactions

Question 10

Process.
f. The resulting P680 is missing negative charge of an electron, thus the solution is ___________ that happens in the ____________.

Answer 10

f. Photolysis; Thylakoid Lumen/Space

Question 11

Photolysis. An enzyme catalyzes
water to split into:

Answer 11

• 2 electrons
• 2 Hydrogen ions (H+)
• 1 oxygen atom

Question 12

Process.
g. From the pheophytin, the electron is now transferred to PSI via the ____________.

Answer 12

electron transport chain

Question 13

Four proteins present in the electron transport chain:

Answer 13

Plastoquinone (Pq)
Cytochrome Complex (cyt)
Protein-plastocyanin (Pc)
Ferredoxin (Fd)

Question 14

Process.
h. The electron transport chain releases _________.
i. the same process happens in _________ as it does in PSII

Answer 14

h. free energy
i. Photosystem I (PSI)

Question 15

Process.
j. Electrons are passed in a series of redox reactions down to the ETC through the protein ___________.

Answer 15

ferredoxin (Fd)

Question 16

Process.
k. ___________ catalyzes the transfer of electrons from Fd to NADP+
l. ___________ are needed
to reduce NADP+ to NADPH

Answer 16

k. NADP+ Reductase
l. two electrons

Question 17

Process.
The energy from the electron fuels membrane pumps that actively move hydrogen ions against their concentration gradient from the stroma into the thylakoid space.

Answer 17

In the electron transport chain
Specifically CYTOCHROME COMPLEX

Question 18

Process.
* Hydrogen ions build up in thylakoid space.
* This potential energy is harvested and stored as chemical energy in ATP through chemiosmosis.

Answer 18

Electrochemical Gradient

Question 19

Process.
The movement of hydrogen ions down their electrochemical gradient through the transmembrane enzyme ATP synthase.

Answer 19

Chemiosmosis

Question 20

Electrons loop back to the first part of the electron transport chain, repeatedly cycling through PSI instead of ending up in NADPH.

Answer 20

Cyclic Photophosphorylation

Question 21

ATP Synthesis relies on the _________, thus when protons leak into the stroma and ruin the gradient, it also ruins the process of ATP synthesis.

Answer 21

proton gradient

Question 22

The process that occurs in PSI only and generates ATP.

Answer 22

Cyclic Photophosphorylation