1. 7 th Grade Life Science

2. Water Cycle Description: A model that describes how water moves from the Earth’s surface to the atmosphere and back again.

3. Carbon and Oxygen Cycles Description: A model that describes how carbon and oxygen molecules move between the living and non-living world.

4. Nitrogen Cycle Description: A model that shows the transfer of nitrogen from the atmosphere to the soil to living organisms and back to the atmosphere.

5. Questions 1. What are the three major processes that occur during the water cycle? EVAPORATION, CONDENSATION, PRECIPITATION

6. Questions 2.What role do producers play in the carbon and oxygen cycles? THEY CONVERT CARBON DIOXIDE INTO OXYGEN 3.What role do consumers play in the carbon and oxygen cycles? THEY CONVERT OXYGEN INTO CARBON DIOXIDE

7. Questions 4.Why do organisms need nitrogen? NITROGEN IS A BUILDING BLOCK OF MATTER THAT MAKES UP LIVING THINGS 5.What is nitrogen fixation and where does it usually occur? NITROGEN FIXATION IS THE PROCESS OF CHANGING FREE NITROGEN IN TO A USABLE FORM OF NITROGEN. IT USUALLY OCCURS ON ROOT NODULES OF CERTAIN PLANTS. THE BACTERIA THAT FIX NITROGEN GET SUGARS FROM THE PLANT AND THE PLANT IS SUPPLIED WITH NITROGEN.