Answer:
Water is a chemical compound and polar molecule, which is liquid at standard temperature and pressure. It has the chemical formula H2O, meaning that one molecule of water is composed of two hydrogen atoms and one oxygen atom. Water is found almost everywhere on earth and is required by all known life. About 70% of the Earth's surface is covered by water. Water is known to exist, in ice form, on several other bodies in the solar system and beyond, and proof that it exists (or did exist) in liquid form anywhere besides Earth would be strong evidence of extraterrestrial life.
Explanation:
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Answer: B. They are a first line of defense that can begin killing pathogens immediately.
Explanation:
B-lymphocytes are not the first line of defense. On the contrary, innate immune cells such as basophils, dendritic cells, eosinophils, Langerhans cells, mast cells are the body's first line of defence.
When blood<span> sugar drops too low, the level of insulin declines and other cells in the pancreas release glucagon, which causes the liver to turn stored glycogen back into</span>glucose<span> and release it into the </span>blood<span>. This brings </span>blood sugar levels<span> back up to normal.</span>
They are held together by weak hydrogen bonds
