Just a general question on some vocab words I cannot piece together myself. Can you provide me with some relevance to some terms used in my biology class literature that I do not understand. Oxidized/oxidation. I understand what these are, but I do not understand their relevance... When you oxidize a compound like ammonia NH3 to NO3...what is the point? does it make energy... is it like an enzyme.. like what does that mean? electron donor/acceptor....why does this matter which is which....? what is the purpose of this besides donating and excepting electrons....? NAD, NADPH... okay I know what these are composed of but what are they exactly and what is their purpose...? some of my definitions say things like \"use CO2\" as main carbon source\" ???? okay.. but what does carbon have to do with anything... how is that energy or food or whatever? Solution 1. ANS: Oxidation: Oxidation is defined as the loss of electrons, hydrogen’s or gain of oxygen atom. If the oxidation taken placed in a cell, then it is called as oxidized. Both the Oxidized/oxidation are same, but the using situation is different. Reduction: Reduction is defined as gain of electrons, hydrogen’s or loss of oxygen atom. Depends upon reaction the redox (oxidation or reduction) will change, sometimes it explains about electrons or in another time it states about oxygen but the sole of the meaning will never change. Ex: Oxidation and Reduction in terms of oxygen transfer Oxidation and Reduction in terms of electrons transfer Oxidation and Reduction in terms of hydrogen transfer 2. ANS: Nitrogen oxidation: It is a process of biological oxidation, in which the anaerobic ammonia (NH4+) and nitrite (NO2-) converts into nitrogen gas (N2). Ammonia is converted into nitrite (NO2-) due to the effect of nitrosomonas bacteria. Nitrite (NO2-) then is converted into nitrate (NO3-) by the influence of nitrobacter bacteria. In this reaction ATP is not released, so the energy is not produced. 3. ANS: Electron donor/acceptor: Electron acceptor: It accept ions that act as oxidizing agents in chemical reactions. Electron donor: It donates electrons, these are reducing agents. The main purpose of this donating and accepting electrons to stabilizes chemical reactions. In biological point of view a series of electron transfer can produce ATP molecules. ATP act like a universal currency. ATP is produced by photon gradient, which is created by ETC in mitochondria. 4. ANS: NAD and NADPH: NAD is a primary oxidizing agents of cell and the NADPH is a primary reducing agents of cell. NAD in oxidation reactions, it accepts two electrons and one photon from the substrate. In reduced form NADPH acts as the primary reducing agent of cell, it donates two electrons and one photon to the medium. 5. ANS: In the photosynthesis reactions plants make glucose by incorporating CO2 and water. The glucose molecule later oxidized in organisms and produced energy in the form of ATP. Foods are mostly composed with carbohydrates.