<P> In plants, algae, and cyanobacteria, photosystem II uses light energy to remove electrons from water, releasing oxygen as a waste product . The electrons then flow to the cytochrome b6f complex, which uses their energy to pump protons across the thylakoid membrane in the chloroplast . These protons move back through the membrane as they drive the ATP synthase, as before . The electrons then flow through photosystem I and can then either be used to reduce the coenzyme NADP, for use in the Calvin cycle, which is discussed below, or recycled for further ATP generation . </P> <P> Anabolism is the set of constructive metabolic processes where the energy released by catabolism is used to synthesize complex molecules . In general, the complex molecules that make up cellular structures are constructed step - by - step from small and simple precursors . Anabolism involves three basic stages . First, the production of precursors such as amino acids, monosaccharides, isoprenoids and nucleotides, secondly, their activation into reactive forms using energy from ATP, and thirdly, the assembly of these precursors into complex molecules such as proteins, polysaccharides, lipids and nucleic acids . </P> <P> Organisms differ according to the number of constructed molecules in their cells . Autotrophs such as plants can construct the complex organic molecules in cells such as polysaccharides and proteins from simple molecules like carbon dioxide and water . Heterotrophs, on the other hand, require a source of more complex substances, such as monosaccharides and amino acids, to produce these complex molecules . Organisms can be further classified by ultimate source of their energy: photoautotrophs and photoheterotrophs obtain energy from light, whereas chemoautotrophs and chemoheterotrophs obtain energy from inorganic oxidation reactions . </P> <P> Photosynthesis is the synthesis of carbohydrates from sunlight and carbon dioxide (CO). In plants, cyanobacteria and algae, oxygenic photosynthesis splits water, with oxygen produced as a waste product . This process uses the ATP and NADPH produced by the photosynthetic reaction centres, as described above, to convert CO into glycerate 3 - phosphate, which can then be converted into glucose . This carbon - fixation reaction is carried out by the enzyme RuBisCO as part of the Calvin--Benson cycle . Three types of photosynthesis occur in plants, C3 carbon fixation, C4 carbon fixation and CAM photosynthesis . These differ by the route that carbon dioxide takes to the Calvin cycle, with C3 plants fixing CO directly, while C4 and CAM photosynthesis incorporate the CO into other compounds first, as adaptations to deal with intense sunlight and dry conditions . </P>

Which reactions in the list below are associated with metabolism