The proterozoic era is defined by the following events: eukaryotic cells first seen stable continents first bacteria fossils the cambrian explosion oxygen building up in atmosphere

Starting at the smallest, most simple level and working your way up to the most complex, explain how the following terms are connected. note-these terms are not in order molecules, atoms, organism, tissues, cells, organ systems, organs

Which of the following best describes the expensive tissue hypothesis? brains require more energy, so the gut had to be reduced, and larger brains and tool use led to higher quality diets. increasing body size means that homo neanderthalensis had to include more fat in its diet. brains require more energy, so the gut had to be reduced as brains got bigger. brains require more fat, so the gastrointestinal viscera (gut) had to expand, and hands were needed to acquire more food.

Which line in the graph above best illustrates an effect of the carbon dioxide level in the blood on breathing rate before, during and after a period of exercise? 1.b,2.c,3.a,4.d