activity

2. any product of the condensation of atmospheric water vapor that is deposited on the earth's surface.
6. kind of nutrient which is needed in a small amount
8. dioxide a colorless, odorless, incombustible gas present in the atmosphere and formed during respiration.
9. a nonmetallic element of the nitrogen family that occurs widely especially as phosphates
10. nitrogen ______. a process in which nitrogen is converted into ammonia.
11. transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction.
12. a long chain of linked sugar molecules. cell walls are made from this rigid material

1. an interval of time during which a sequence of a recurring succession of events or phenomena is completed.
2. is a process used by plants and other organisms to convert light energy, normally from the sun, into chemical energy.
3. the air we use for respiration; the 21 percent portion of the atmosphere
4. makes up 78 percent of the atmosphere.
5. ____cycle. the another term for water cycle.
6. required by organisms in such large quantities
7. the process by which ammonium gets changed into nitrates by bacteria.