Photosynthesis and Light Dependent Reaction Part 1

Question 1

What are the two steps Photosynthesis is divided into?

Answer 1

1. The Light Reactions (Noncyclic electron flow).
2. The Calvin Cycle (Cyclic electron flow).

Question 2

What is the Photosystems within the Light Reactions?

Answer 2

• They are embedded in the thylakoid membrane.
• They contain chlorophyll and accessory pigments that are associated with proteins.
• Consists of an antenna complex.

Question 3

What is the Antenna Complex?

Answer 3

It absorbs a photon and transfers energy to the reaction centre.

Question 4

What does the Reaction Centre contain?

Answer 4

Contains chlorophyll a, whose electrons absorbs energy and begin photosynthesis.

Question 5

What does the photosystem II (P680) do?

Answer 5

• 2 photons strike photosystem II and excite 2 electrons from chlorophyll P680.
• The excited electrons are then captured by a primary electron acceptor and are transferred to plastoquinone and the ETC.

Question 6

What is the role of the Q Cycle of Photosystem II?

Answer 6

The Q cycle transports 4 protons from the stroma into the thylakoid lumen to create a proton gradient.

Question 7

What drives the Photophosphorylation of ADP to ATP?

Answer 7

The electrochemical gradient drives photophosphorylation of ADP to ATP.

Question 8

What does the Z protein split into?

Answer 8

It splits into 2 protons and 2 electrons as well as 1 oxygen atom.
- Electrons replaces those lost from chlorophyll P680.
- Protons remain in the thylakoid lumen to add to the proton gradient.
- Oxygen leaves as a byproduct.

Question 9

How does 1 NADP+ get reduced to 1 NADPH?

Answer 9

An enzyme NADP reductase would use 2 electrons and a proton from the stroma to reduce 1 NADP+ to 1 NADPH.