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2

No. Lungs are a feature of tetrapods (land vertebrates) and some lungfish. Many fish have swim bladders, which are thought to be homologous to lungs (they evolved from the same ancestral structure) but are not lungs, and I don't think they come in pairs anyway. Some other air-breathing organisms evolved air-breathing structures that also get called "...


1

There are several lines of evidence. Behavior, we regularly eat meat. This is the one that matters most, omnivore is a behavioral classification. All humans societies eat meat, a few eat little else or nothing else. The fact that a small subset of well off people in developed countries don't does not change this. Our two closest relatives also eat meat and ...


4

It is about the movement of the bone along its major axis of movement. A hinge joint moves like a lever while a pivot joint involves rotation side to side like an axle. It helps if you look at a example of a bone that has both types of joints. The radial head is part of both a pivot and hinge joint, with the ulna it rotates allowing the hand to pronate and ...


3

The mesencephalic nucleus of trigeminal nerve is involved with reflex proprioception of the periodontium and of the muscles of mastication in the jaw that functions to prevent biting down hard enough to lose a tooth. To subserve this reflex protective function, mechanoreceptive nerves in the periodontal ligament sense tooth movement and project to the ...


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