Light does one job: it lifts an electron. Everything else — the gradient, the ATP, the sugar — is that one push being converted into something a cell can keep.
Photosynthesis is not one reaction. It is a light-powered stage that makes ATP and NADPH, and a second stage that spends them on carbon — in a different part of the chloroplast.
Water in, oxygen out, ATP and NADPH produced. Requires light and a membrane to hold a gradient across.
CO₂ in, sugar out. Needs no light directly, but stops within minutes without the products of stage one.
Energy and reducing power. The empty carriers return, so the two stages regulate each other in both directions.
Tap each part. Pay attention to the return arrow — it explains why blocking one stage stops the other.
Tap either stage, the ATP or NADPH arrows, the return arrow, or the naming note.
From a split water molecule to NADPH, through both photosystems. Watch where the electron loses energy — that is where the proton gradient is built.
Follow the carbon and the arithmetic together. The cycle spends most of its ATP rebuilding its own starting material.
Exams rarely ask you to recite the pathway. They ask what accumulates and what disappears when something is removed.
Anything made before the block builds up. Anything made after it falls. Say which molecule and in which direction.
Blocking the Calvin cycle also stops the light reactions, because NADP⁺ and ADP stop coming back.
Remove CO₂ and RuBP accumulates while G3P falls. Remove light and the reverse happens.
Tap a node to light up its connections. The pink dashed link is the one that mirrors respiration exactly.
Light energises an electron; everything else is that energy being converted, stored and spent.
Drag a term into a gap, or tap a term and then tap a gap. Two terms belong nowhere.
The light reactions take place in the membrane, where water is split by to replace lost electrons. As electrons fall down the transport chain, protons are pumped into the lumen, creating a . Protons then flow back through ATP synthase, making ATP by . The final electron acceptor is NADP⁺, forming . Both products are released into the , where the enzyme fixes carbon dioxide onto the five-carbon molecule .
Single best answer. You get the reasoning as soon as you commit.
Biology by Bradford