Lecture 6: Photon conversion into electrical and chemical energy

Question 1

What are the reactants in photosynthesis?

Answer 1

6 CO2, 6H2O and light

Question 2

What are the products of photosynthesis?

Answer 2

Sugar (glucose) and 6O2

Question 3

What are the main energy carriers in photosynthesis?

Answer 3

ATP, NADPH

Question 4

What happens in photosystem II (P680) (the first photosystem)

Answer 4

The chlorophyll molecules are excited by light and transfer energy to the reaction center complex. The electron there is boosted to a higher energy state and passed down an electron transport chain. P680 becomes P680+, which gets reduced by the splitting of water (thus releasing oxygen as a by-product).

Question 5

Where do the ATP and NADPH created during photosynthesis go?

Answer 5

The Calvin Cycle

Question 6

Where does photosynthesis take place?

Answer 6

In the thylakoid membrane. Thylakoids are located in the stroma of chloroplasts, which are found in plant cells.

Question 7

Where does the Calvin cycle take place?

Answer 7

stroma

Question 8

What happens as the electrons during photosynthesis go down the electron transport chain to photosystem I?

Answer 8

The energy liberated is used to pump H+ into the thylakoid, which drives ATP synthesis as H+ diffuses back into the stroma.

Question 9

What happens during the Calvin cycle?

Answer 9

Also known as the dark reactions, the Calvin cycle utilizes the energy made during the light-reactions (ATP & NADPH) to fix C from CO2 to organic compounds, producing glucose.

Question 10

How do artificial leaves work?

Answer 10

Split water on a silicon platform using certain catalysts, generating H2 which can be used as an energy source. This water splitting is achieved by a proton-coupled multi-electron transfer process.

Question 11

What are some disadvantages of solar fuel production through artificial photosynthesis?

Answer 11

• materials corrode in water
• significantly more costly than fossil fuels
• materials used are unsustainable