Please help answer as best you can alot of points.

Taxonomy helps "classify", or group animal or plants with similar traits together. These can be general groups such as mammals, to extremely specific, such as humans. This helps us understand that while there are differences in groups, they are all inherently the same in one way or the other. Scientists generally use Taxonomy to find similarities in between species and while they classify correctly, they use the information wrongfully. For example, while we may share characteristics with Apes, and that may be a good example of Taxonomy, but when they bring it more into the grey zone and say "we descended from Apes", it is almost false. We do not see Apes becoming humans, neither humans returning to be Apes. Science always states that they don't want "beliefs, but rather, hard facts". Science is a fallacy in itself, as it itself assumes many things, and states them as "facts", when in reality, they are far from it.

Oxygen is important to each and every organism, as people and animals use it as a "fuel" to burn nutrients that was consumed. Humans intake oxygen typically from their noses or mouths, and it goes into the lung and then heart, where oxygen is sent to different parts of the body when needed, and carbon dioxide is repumped out to the lungs to be exhaled. Flatworms obtain oxygen throughout their body, obtaining oxygen from the water (built by two Hydrogen, one oxygen). Ferns do not essentially need oxygen. Instead, they need carbon dioxide to help them survive. Oxygen is what they "exhale", or the finished product.

Three kinds of wastes that humans must remove is:

Carbon dioxide: High levels of Carbon Dioxide can be extremely harmful to the human body, and may lead to death:

Solid Waste: If waste is not removed, it may lead to infection, breeding grounds for bacterias, and overall harm for the body.

Liquid Waste: This is the same as solid waste.

Waste removal is important in the human body, as it keeps the body from keeping in any "poisonous substances", and keeps the waste from being a breeding ground for germs and bacterias. Disposing of waste can also bring out any germs or bacterias that were unwelcomed inside, and is a benefit to the body overall.

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all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex