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.

this protocol provides a detailed procedure for co-immunoprecipitation (co-ip) to identify protein–protein interactions.

the scientific method.