AP BIOLOGY

Detailed explanation-1: -In photosynthesis, a light-dependent reaction uses light energy from the sun to split water which has been taken in by the organism. Water, when split, gives oxygen, hydrogen, and electrons. These electrons move through structures in chloroplasts and, by chemiosmosis, make ATP.

Detailed explanation-2: -In a process called photolysis (’light’ and ‘split’), light energy and catalyst s interact to drive the splitting of water molecules into protons (H+), electrons, and oxygen gas.

Detailed explanation-3: -Water is used to provide hydrogen ions and electrons but also produces oxygen. The electrons and protons are used to produce NADPH (the reduced form of nicotine adenine dinucleotide phosphoric acid) and ATP (adenosine triphosphate). ATP and NADPH are energy storage and electron carrier/donor molecule.

Detailed explanation-4: -Water is split on the thylakoid lumen side of the thylakoid membrane, so the protons are released inside the thylakoid, contributing to the formation of a gradient. The high-energy electron travels down an electron transport chain in, losing energy as it goes.