when a plant manufactures oxygen,  where from does the oxygen come? from the carbon dioxide or from the water?
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Water photolysis\nThe NADPH is the main reducing agent in chloroplasts, providing a source of energetic electrons to other reactions. Its production leaves chlorophyll with a deficit of electrons (oxidized), which must be obtained from some other reducing agent. The excited electrons lost from chlorophyll in photosystem I are replaced from the electron transport chain by plastocyanin. However, since photosystem II includes the first steps of the Z-scheme, an external source of electrons is required to reduce its oxidized chlorophyll a molecules. The source of electrons in green-plant and cyanobacterial photosynthesis is water. Each water molecule is oxidized by four successive charge-separation reactions by photosystem II to yield a molecule of diatomic oxygen and four hydrogen ions; the electron yielded in each step is transferred to a redox-active tyrosine residue that then reduces the photooxidized paired-chlorophyll a species called P680 that serves as the primary (light-driven) electron donor in the photosystem II reaction center. The oxidation of water is catalyzed in photosystem II by a redox-active structure that contains four manganese ions; this oxygen-evolving complex binds two water molecules and stores the four oxidizing equivalents that are required to drive the water-oxidizing reaction. Photosystem II is the only known biological enzyme that carries out this oxidation of water. The hydrogen ions contribute to the transmembrane chemiosmotic potential that leads to ATP synthesis. Oxygen is a waste product of light-independent reactions, but the majority of organisms on Earth use oxygen for cellular respiration, including photosynthetic organisms.\n\n\nOxygen and photosynthesis\nWith respect to oxygen and photosynthesis, there are two important concepts.\n\nPlant and cyanobacterial (blue-green algal) cells also use oxygen for cellular respiration, although they have a net output of oxygen since much more is produced during photosynthesis. \nOxygen is a product of the light-driven water-oxidation reaction catalyzed by photosystem II; it is not generated by the fixation of carbon dioxide. Consequently, the source of oxygen during photosynthesis is water, not carbon dioxide.
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In Photosynthesis, plants use the sun's energy as light to transform carbon dioxide and water into glucose.  In cellular respiration,  glucose is ultimately broken down to yield carbon dioxide and water, and the energy from this process is stored as ATP molecules.
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Plants dont take away oxygen, they make it.\nPlants taking in what animals and humans breath out and proscesses it through their systems and make it oxygen.\nTry the link-
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in respiration a cell turns glucose and Oxygen into waaste products CO2 and H20. That is why we breathe in oxygen and breathe out carbon dioxide. In photosynthesis a plant makes glucose and Oxygen from our waste products.
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It is called photosynthesis.\nThe reaction is:\n6CO2 + 6H2O (+ light energy)----> C6H12O6 + 6O2\n\nIn this reaction the plants convert the carbon-dioxide and water into glucose releasing oxygen.
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Plants are living things, and like us, need noses to breathe.  The 'noses' of plants are tiny holes called stomata (s), stoma (p) at the underside of leaves.  These stoma help the plant exchange gases with its surrounding.  Oxygen is produced during the day as the byproduct of photosynthesis, when the plant takes in carbon dioxide in the presence of sunlight to make food.  At night, the plant rests and does not make any more food, thus consuming oxygen.  This whole process is called respiration.
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the answer is CARBON DIOXIDE
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Photosynthesis does *not* produce carbon dioxide. Photosynthesis uses energy from the sun to combine CO2 and H2O to make glucose. Respiration breaks down glucose for energy and gives off CO2.
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Water is just a liquid gas isn't it? Hydrogen and Oxygen mixed makes water. That's how.
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In B, oxygen is a waste product of photosynthesis, but oxygen can also be produced in D. In electrolytic cells the electrolysis of salt water or acidic water is an  example of electrolysis. The ionic solution is driven by current and produces hydrogen gas in a reduction reaction at the cathode using electrons to complete the hydrogen ions. At the anode OXYGEN gas is produced in an oxidizing reaction and electrons are given off as the oxygen ions combine.
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Photosynthesis , basically occurs in two distinct phases. 1) Light reaction & 2) Dark reaction\n            Both are part of photosynthesis\n6CO2 + 12H2 O -> LIGHT &   CHLOROPLAST> = C6 H12 O6 + 6H2 O + 6O2\nThe above is the often quoted equation of the process\n            1) Light reaction or the Hill’s reaction occurs in the grana of a chloroplast.\n  Sun’s light energy is used to convert ADP in to ATP …………. (i)\n   NADP is converted in to NADP. H2…………………………… (ii)\n It can occur only in the presence of light, hence the name.\n2) Dark reaction or Calvin’s cycle occurs in the stroma of a chloroplast.\n   Light plays no role in it. Hence  called dark reaction.\n  With the help of the two products of light reaction, i.e. ATP & NADP.H2 glucose is manufactured from CO2 and H2 O  i. e. carbon dioxide gas and water.\nThe CO2   in the above equation comes from the atmosphere and enters through the stomata on the leaves.\nThe H2 O  in above equation comes from the soil through the roots, stem and xylem elements.\n A single molecule of Glucose (C6 H12 O6) requires all the six molecules of carbon dioxide gas but only 50% of water ( Only 6 out of 12 H2 O molecules entering the reaction (see the equation)\nRemaining 50% water ( The water you are talking about, I presume) and the O2 gas is released back in the atmosphere as a byproduct ( and not waste product) . There is no room for waste in the nature.\nIt is wholly man made and he is paying for that and will continue to pay dearly  for his tampering with the Nature!\n\n\nEdit---> The 50% water that is released in the atmosphere through the stomata comes from the soil...................(1)\n\n              This is recombined water, after spltting of the orginal water molecules in to hydrogen and oxygen to extract electrons \nfor the manufacture of ATP and NADP.H2...................(2)\n\nIn short, all the molecules out of the 12 original are utilised \none way or the other..................(3)
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When a plant (a collection of cells) metabolizes and goes through its respiration, it requires carbon dioxide. It gives off oxygen as a by-product.\n\nWhen an animal (a collection of cells also) metabolizes and goes through respiration, it requires oxygen and gives off carbon dioxide.
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Oxygen, Carbon Dioxide, and Water
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Plants use the energy of sunlight to grow using a process call photosynthesis (light - putting together) taking in carbon dioxide from the air and giving up oxygen.  At night the light of the moon (reflection of sunlight) is too weak to support photosynthesis and the plant actually uses oxygen rather than make it.
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Well, basically in photosynthesis, it takes in carbon dioxide, water, and sunlight (or energy). Then it is made into glucose. And after the glucose is made, cellular respiration begins. The oxygen in the water is released from the plant into breathable air. Then humans inhale the air and let out carbon dioxide. It is really a neverending process when you think about it.\n\nWhere does the plant get that water?\nWell, when you water your plants, you're giving it the water it needs for photosynthesis and cellular respiration.\n\nWhat is the extra glucose (which is food for the plant and is also known as a type of sugar) stored as?\nThe extra glucose can be stored as starch, if not eaten by the plant.\n\nI hope this has helped you!\n\n-Fulla Questions :)
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I would say it is the leaf of a plant or the plant itself.  The leaf gives off oxygen (the waste product) during photosynthesis.\n\nOr: (I grabbed this off Wikipedia)\nphotosynthesis uses water as an electron donor which is oxidized into molecular oxygen by the absorption of a photon by the photosynthetic reaction centre.
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Trees are phototrophs, they produce their own food by using carbon dioxide, water, and sunlight.