1. Cycles of Matter

2.  What is the function of the water cycle? It moves water from Earth's surface to the atmosphere and back.  What are the three processes that move water between Earth's surface to the atmosphere and back? Evaporation, condensation, precipitation.  Evaporation: process by which liquid water absorbs energy and changes to gas.  Condensation: a gas changes to liquid.  Precipitation: as more water vapor condenses heavy drops fall to earth as precipitation: rain and snow

3.  How are Carbon, oxygen, and nitrogen recycled?  The carbon cycle is the process by which Carbon moves within and between organisms and their physical environment.  The oxygen cycle is the process by which oxygen moves through ecosystems.  Human activities cause the levels of carbon dioxide in the atmosphere to rise.  Like carbon and oxygen, nitrogen is recycled in ecosystems. Most organisms can use nitrogen only after it has been fixed, or combined with other elements to form nitrogen containing compounds.

4.  How do living systems conserve matter and energy?  Living systems conserve matter and energy through the process of photosynthesis and respiration.  According to the conservation laws, the total amount of matter and energy in the Earth system space constant.  As plants and animals grow, they do not use up matter.