Fossil evidence indicates that the first organisms on Earth were single-called prokaryotes. The first eukaryotes are believed to have formed from these prokaryotes. How does the endosymbiotic theory explain the development of the first eukaryotic organisms?.

The endosymbiotic theory explains how eukaryotic cells evolved. The large and small cells formed a symbiotic relationship in which both cells benefited. Some of the small cells were able to break down the large cell's wastes for energy. They supplied energy not only to themselves but also to the large cell.

they float because they are less dense than the water itself

something denser than water, like a rock, will sink to the bottom

kelp are large brown algae that live in cool, relatively shallow waters close to the shore. they grow in dense groupings much like a forest on land. these underwater towers of kelp provide food and shelter for thousands of fish, invertebrates, and marine mammal species.

e) all of the above