In addition the oxygen in the Earth's atmosphere absorbs wavelengths at the edge of the ultra-violet region of the spectrum. The resulting color, which appears like a pale blue, actually is a mixture of all the scattered colors, mainly blue and green.
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<span>NA contains only elements, so it does not react easily. Many organisms do not contain DNA. Certain mutations in DNA happen at a constant rate. DNA does not change over time, making it a valuable clue.</span>