Answer: "natural selection" .
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<span><em>Whether living or non living:</em>
<em>When you put a sample of tissue under a microscope, if u can see a cell membrane, and can identify some cell structures like nucleus, mitochondria, vacuoles etc. , it was living, if not, its a non living thing.</em></span>
<span><em>However some cells don't have a nucleus( eg. prokaryotic cells), but all cells have a cell membrane or some sort of protective covering to contain the cell's insides. </em></span>
<span><em>To check if your specimen maybe-once living, maybe-still living "something", is living, get a look at it through an electron microscope - thats the best microscope ever- and see if the mitochondria's making any ATP( adenosine triphosphate, source of energy for most organisms), if it does, its living. If not, no</em></span><em>n living. :)</em>
The is not a link for me to see lad.
Answer:
via hydrogen bonds; there are two between adenine and thymine and three between cytosine and guanine
