the answer is 21<span>% oxygen, </span>
I mean, there's plenty of differences between muscle and nerve cells. For one, they serve different functions. Nerve cells react and send stimuli rapidly through action potentials, functioning in the nervous system and allowing the brain to communicate with the rest of the body, while muscle cells allow muscles to move. Another difference is the structure of the cells, with nerve cells having dendrites, axons, and neurotransmitters to assist in the firing of action potentials. You're going to have to be a little more specific, I can't really help you any more with such a broad question.
Miller Urey experiment mimics the environment we had for earth billion of years ago. They put in inorganic molecules and came out with organic molecules. Other scientist thought that they messed up their experiment, but once other scientists recreated and tested. They saw that Miller and Urey were correct. And that helped them see that the origin of life can come from simple cells.
<span>Protista and Eubacteria so the last one.</span>
Cell theory was fdiscovered in the 17th century. but the first. cell theory was credited in the 19th century.