1) earth is considered a system because all of its parts_.
a: represent separate closed systems
b: interact
c: where formed at the same time
d: are powered by the same energy source
2) what are the 2 sources of energy for the earths system?
a: lightening and the sun
b: the sun and the earths interior
c: the sun and wind
d: earths interior and wind
3) which of the following is not caused by human interactions with the earths system?
a: air pollution
b: water pollution
c: mountain building
d: deforestation

This is a typical grassland food web. it is also a small picture of an important cycle on earth: the carbon cycle. describe how the carbon gets into this food web. a) bacteria and fungi, the decomposers, recycle carbon from dead organisms. b) carbon is found in the grass and is passed from one level to the next in this food web. eliminate c) all living things give off carbon dioxide as a by-product of respiration and it is released into the atmosphere. d) plants use carbon dioxide as a reactant in photosynthesis, to make usable chemical energy in the form of a sugar.

Wich of the following are manual restraint techniques for dogs

Which of the following is a reason why early living organisms on earth could not have survived on the surface? 1. the lack of an ozone layer 2. the lack of oxygen in the atmosphere 3. the fact that these organisms were single-celled