Membranes are barriers and “gatekeepers”, they only let certain molecules pass through them.
they also transport nutrients to the cell
Answer:
Silicon
Explanation:
A period is the horizontal row of elements on the periodic table.
Answer:
The sample obtained from the environment has a higher mass
Explanation:
A simple way to put the answer is that the element carbon -as found in nature- has a molar mass of 12.0107 g/mol, because there are a few isotopes of 14C and 13C; and <em>the molar mass is an expression of the isotopes' natural abundance</em>.
So 1 mole of carbon obtained from the environment would weigh 12.0107 g, while a sample of isotopically pure carbon would weigh 12.0000 g.
Answer:
Alcohol in Your Body
Alcohol reaches your brain in only five minutes, and starts to affect you within 10 minutes. After 20 minutes, your liver starts processing alcohol. On average, the liver can metabolize 1 ounce of alcohol every hour.
Explanation:
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