Light-Harvesting Reactions (Set 2/6)

What are the main products of the light reactions?

ATP, NADPH, and oxygen (O2).

What is the original source of electrons in photosynthesis?

Water (H2O).

What happens when water is split during the light reactions?

It releases electrons, hydrogen ions (H+), and oxygen (O2).

What does water provide during photosynthesis?

Electrons.

What does carbon dioxide provide during photosynthesis?

Carbon used to build sugars.

What does sunlight provide?

Energy.

What is ATP?

A molecule that provides usable energy for cellular processes.

What is NADPH?

An electron carrier that delivers high-energy electrons to the Calvin Cycle.

What is Photosystem II?

The first photosystem; it uses light energy and replaces lost electrons by helping split water.

What is Photosystem I?

The second photosystem; it re-energizes electrons to help produce NADPH.

Which photosystem works first?

Photosystem II, then Photosystem I.

What is the electron transport chain in photosynthesis?

A series of proteins that transfer electrons and help pump H+ ions into the thylakoid space.

Where do H+ ions build up during photosynthesis?

Inside the thylakoid space.

What is a proton gradient?

A difference in H+ concentration across a membrane.

What is ATP synthase?

A protein that uses the flow of H+ ions to make ATP.

What is chemiosmosis?

The movement of H+ ions through ATP synthase to help produce ATP.

How is ATP made during the light reactions?

H+ ions build up in the thylakoid space, then flow through ATP synthase, which makes ATP.

What is the relationship between light reactions and the Calvin Cycle?

Light reactions make ATP and NADPH, which the Calvin Cycle uses to build sugars.