Question

Photosystems

Photosystems: 1. Circle the letter of each sentence that is true about the light-dependent reactions. Correct the false statements. a. They convert ADP into ATP. b. They produce oxygen gas. C. They convert oxygen into carbon dioxide. d. They convert NADP* into NADPH. 2. Where do the light-dependent reactions take place? 3. What happens to water in the light-dependent reactions?

Answer 1

1) during light reactions the electrons from the PSII is excited and it is transported via electron transport chain, using the energy of the electron proteins in the electron transport chain pumps H+ from the stroma to the thylakoid lumen so H+ concentration in the thylakoid increases, generating an H+ gradient, finally, the electrons are used to reduce NADP+ to NADPH, the H+ gradient generated is used by the ATP synthase to make ATP from ADP and Pi. as electrons from the PSII is transported via electrons transport chain the water is split to H+, electrons, and oxygen the electrons released in this process is used to replace the electrons lost from the PSII.

a) True, ATP is produced from ADP

b) True, oxygen is produced from water.

c) False, they convert water to oxygen ( carbon dioxide is fixed in the dark reactions)

d) True, NADP+ is reduced to NADPH.

2) light reactions take place in the thylakoid membrane and the thylakoid lumen, that is in thylakoid.

3) water is split to H+, electrons, and oxygen using the energy of light, the water splitting complex is associated to PSII.