The light dependent reaction first stage

where do light-dependent reactions take place?

In the thylakoid membrane of the chloroplast

what is the chloroplast?

an organelle in plant cells where photosynthesis occurs; contains thylakoids with chlorophyll to capture light and produce energy.

what is the thylakoid?

A flattened membrane sac inside chloroplasts where the light-dependent reactions of photosynthesis take place

what is the chlorophyll?

The green pigment in the thylakoid absorbs light energy for photosynthesis.

what is the main purpose of the light-dependent reactions?

to convert light energy into chemical energy in the form of ATP and NADPH

What happens to water during the light-dependent reactions?

It splits(photolysis) into electrons, protons(H+) and oxygen

what gas is released as a by-product of the light dependent reaction?

oxygen(o2)

what is the stroma

The fluid inside chloroplasts

what is the stromata

Tiny pores on a leafs surface that open and close to allow gas exchange and water vapor out.

what is a light dependent reaction

The first stage of photosynthesis that uses light to make ATP and NADPH and releases oxygen from water

what is the role of Photosystem II

Absorbs light → excites electrons → electrons move to the electron transport chain.

what happens to the electrons move down the electron transport chain

energy from electrons pumps H+ ions into the thylakoid space, building a proton gradient

what enzyme makes ATP

ATP synthase

How does ATP synthase work

H+ ions flow down their gradient through the enzyme→ ATP is produced from ADP + Pi.

what is the role of photosytem I

Absorbs light → re-excites electrons → electrons are used to reduce NADP⁺ into NADPH.

what two energy-rich molecules are produced

ATP and NADPH

where do ATP and NADPH go after being made

in the stroma

what is the order of light dependent reactions

1. Light hits Photosystem II (PSII)
   – Electrons get excited.

2. Water splits (photolysis)
   – Replaces electrons in PSII; oxygen is released.

3. Electrons move through the electron transport chain (ETC)
   – Energy pumps H⁺ ions into the thylakoid.

4. H⁺ ions power ATP synthase
   – ATP is produced.

5. Light hits Photosystem I (PSI)
   – Electrons are re-energized, comes from the splitting of water from PSII, 2 hydrogen ions, 2 electrons and 1 oxygen.

6. Electrons reduce NADP⁺ → NADPH
   – Final energy product of PSI.