A dog which wakes up and goes hunting in the absence of any change in its surroundings. Briefly compare bacteria and humans in terms of each of these three characteristics. Bacteria and humans are both currently living organisms, so must be regarded as comparably well-adapted to the environment. Bacteria are, however, simpler, in the sense that they consist of single bounded cells without membrane bounded internal compartments, whereas humans consist of multiple cells each with bounded internal compartments. Bacteria also appeared earlier in evolution 14.
Vertebrates have in common an endoskeleton and a dorsally located nervous system.
Arthropods have in common an exoskeleton and a ventrally located nervous system. There are no known animals with an endoskeleton and a ventrally located nervous system. This may be because such animals existed but are now extinct, or maybe because such organisms have not yet been tried during the evolutionary process. Give two reasons for suggesting that life, as we currently see it on earth, is partly the result of chance events, i.e., that it would likely be different, at least in detail, if it exists elsewhere in the universe An important component of the history of life is the random change of genetic material on which natural selection acts. Evolutionary change also appears to depend on such unpredictable events as the collision of a meteor with the earth.