My best guess would be c because b makes no since we as humans do not have photosynthesis and are considered living organisims, d is also wrong because the brain requires oxygen, and its not a because the brain is made of cells.
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:
B. The carbon cycle
Explanation:
In the carbon cycle, carbon in the atmosphere is absorbed into plants, where the plants use photosynthesis to convert that carbon into oxygen and energy for themselves. Neither of the other cycles involves a plant taking in a gas directly from the atmosphere.
Hopefully this was helpful! :)
The answer is B) These fuels are available in a limited supply- - when the fuel is used it is no longer available.
B according to my school.