Lungs have a pulmonary circulation
Skin color<span> is due primarily to the presence of a pigment called melanin , which is controlled by at least 6 genes. Both light and dark complexioned people have melanin. However, two forms are produced--pheomelanin , which is red to yellow in</span>color<span>, and eumelanin , which is dark brown to black</span>
Answer:
1. Purines
2. States that DNA composition varies among species
3. Hydrogen Bond
4. Purines
<em>Answer to #2 is a little iffy </em>-- sorry
Explanation:
Pyrmidines have two rings
Purines have one ring
Complementary bases are connected by hydrogen bonds.
Answer:
Without naturally occurring greenhouse gases, Earth's average temperaturewould be near 0°F (or-18°C) instead of the much warmer 59°F (15°C). The concentration of greenhouse gases, especially carbon dioxide and methane, has fluctuated naturallyover geological time scales.