50 points
discuss the importance of oxygen to all living organisms, and describe how three different organisms—human, flatworm, and fern—obtain the oxygen they need

Hey hope this helps.

Explanation:

It allows the process of respiration to occur. For humans we inhale oxygen and exhale carbon dioxide. For the flatworm it does the same it inhales oxygen and exhales carbon dioxide. Now for a fern since it is a plant it can not take in oxygen it can only release it. This happens through photosynthesis. It is where plants take in the carbon dioxide and release oxygen.

1 and 6 for apex

hydroxyl -oh

alcohols, always polar, can form hydrogen bonds with h2o molecules

carboxyl -cooh  

cargoxylic acids, has acidic properties which is a source of hydrogen ions, found in cells in ionized for with a charge of oh-1

carbonyl > co

ketone if within skeleton, aldehyde if group is at the end of skeleton, k & a may be structural isomers, it determines 2 sugars (ketose & aldose)

amino -nh2

amines, acts as a base, it can pick up h+ ions from surrounding solution, ionized with charge of 1+

methyl ch2

addition to rna/dna affects and gene expression

phosphate -opo3 ²⁻

organic phosphates, contributes to negative charge to, molecule that it is a part of, and potential to react with h20

sulfhydryl -sh

thiols, cross-linking stabilize the protein, and it is structure