They can survive through homeostasis, the balancing of the internal temperature of the cell. <span />
Answer: <u>Guanine
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According to Chargaff's rule, the base pairing in the DNA and RNA is fixed. Adenine always pairs with Thymine in DNA and Uracil in RNA. Guanine pairs up with cytosine. This complementary base pairing is universal and constant. That's why amounts are also equal. It means if cytosine is 20% in any DNA sample, then amount of guanine would be 20% as well.
The double membrane. It's theorized that chloroplasts used to be their own single-celled organism in the environment (and therefore with its own membrane). Then, the theory states, a larger cell took in the chloroplast by endocytosis, which involves surrounding the chloroplast in the large cell's own membrane. The chloroplast would then have two membranes surrounding it. This is similar to the thinking for mitochondria becoming an organelle as well. Hope this helps! :)
