What's the question here?
B - To live in less extreme environments than most Archaebacteria.<span>♥</span>
Cellular pathology as based upon physiological and pathological histology
B.) Adenine because Dictated by specific hydrogen bonding patterns, Watson-Crick base pairs (guanine-cytosine and adenine-thymine) allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence.
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The cell has to use active transport when it's trying to transport material against the concentration gradient. (from low to high concentration) Or, if a molecule is too big to diffuse through the cell membrane, it must be moved through using a carrier protein.
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