Oxygen first began to accumulate in Earth's atmosphere as a result of ____
A) biosynthesis
B) cellular respiration
C) methane synthesis
D) photosynthesis
D
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We deal with toxic substances every day. All of the following are methods used to limit risk from exposure to toxic substances EXCEPT
A. establishing a level (threshold level) below which exposed test animals show no reaction. B. setting limits to the amount of exposure a person is allowed to receive in the workplace. C. subjecting test animals to a substance to see if they become ill or die. D. prohibiting the use of toxic substances by the public.
Match water-cycle terms that are most closely related.
- Infiltration
- Melt Water
- Precipitation
- Runoff
- Transpiration
- Water Vapor
Group B:
- Gas
- Groundwater
- Ice
- Plants
- Rainfall
- Stream
What mountain range in Europe is over 500 miles long and has peaks reaching 15,000 feet?
A) Pyrenees B) Alps C) Carpathians D) Himalayas E) Apennines
____________________ ____________________ ____________________ consisting of ice and frozen nitrogen compounds form over Antarctica in June
Fill in the blank(s) with correct word