| A | B |
|---|
| ammonia | one form of nitrogen that is usable by plants and animals |
| combustion | the burning of fossil fuels that releases carbon into the air |
| condensation | the process of water vapor changing back into liquid water droplets as a result of cooler temperatures at higher altitudes, forms a cloud |
| evaporation | the process of the water on Earth’s surface changing into water vapor as a result of being heated by solar energy |
| fixed | changed |
| fossil fuels | coal, petroleum and natural gas formed over millions of years from the carbon of dead plants and animals |
| ground water | precipitation that is absorbed into the ground where it eventually seeps through the ground into rivers, lakes or oceans |
| nitrates | one form of nitrogen that is usable by plants and animals |
| nitrogen | an element that is needed by all living things to make protein |
| nitrogen cycle | the process by which nitrogen moves though living things and the environment |
| photosynthesis | the process by which plant cells use carbon dioxide and solar energy to make food in the form of sugars, oxygen is released into the air as a byproduct |
| precipitation | rain, sleet, hail, snow |
| respiration | animals breathe in oxygen and breathe out carbon dioxide |
| runoff | precipitation that flows over Earth’s surface into rivers, lakes and oceans |
| solar energy | energy from the sun the provides the energy for photosynthesis in plants |
| transpiration | the process where plants draw water up through the roots into the stem and then through the leaves where it evaporates into the air |
