Water is split (oxidized) during the light-dependent reactions of photosynthesis in a process called photolysis, releasing oxygen as a byproduct. This occurs in the thylakoid membrane of chloroplasts, and the electrons from water replenish the lost electrons from Photosystem II.

The C4 pathway, found in plants like maize and sugarcane, minimizes photorespiration by concentrating CO2 in bundle sheath cells where RuBisCO is located. This is particularly advantageous under high temperature and light intensity, where photorespiration rates are higher in C3 plants.

RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is the enzyme responsible for carbon fixation in the Calvin cycle. It catalyzes the reaction between CO2 and RuBP to form 3-PGA, the first stable product of the cycle.

In C3 plants, an increase in oxygen concentration leads to higher photorespiration because RuBisCO can bind to oxygen instead of CO2. This reduces the efficiency of carbon fixation and thus decreases the rate of photosynthesis.

Cyclic photophosphorylation involves only Photosystem I and results in the production of ATP via a cyclic electron flow. Non-cyclic photophosphorylation, on the other hand, involves both Photosystem I and II, producing ATP, NADPH, and oxygen using water as an electron donor.

The Calvin cycle is termed light-independent because it does not directly require light to function. However, it depends on ATP and NADPH, which are produced during the light-dependent reactions in the thylakoid membranes, to power the synthesis of glucose.

Carotenoids are accessory pigments that protect chlorophyll from photooxidation by dissipating excess light energy as heat, especially under high light intensity. They also assist in light absorption and transfer energy to chlorophyll molecules.

In CAM (Crassulacean Acid Metabolism) plants, carbon fixation occurs at night when stomata are open, allowing CO2 uptake while minimizing water loss due to lower temperatures and higher humidity. The fixed carbon is stored as malic acid and used in the Calvin cycle during the day when stomata are closed.

During the light-dependent reactions, water molecules are split (photolysis) in the thylakoid membrane, releasing oxygen atoms that combine to form molecular oxygen (O2). This O2 is released into the atmosphere as a byproduct of photosynthesis.

The Z-scheme describes the linear (non-cyclic) electron transport pathway in light-dependent reactions, where electrons flow from water (via Photosystem II) to NADP+ (via Photosystem I), generating ATP and NADPH. The 'Z' shape represents the energy levels of electrons as they are excited and transferred.