1. Section 13-3

2.  Food Chains: sequence of organisms related to one another as food and consumer  Food Webs: interconnecting food chains in an ecological community

3.  Organisms need more than just energy to survive; they also need nutrients  Nutrients: substances organisms use to build living tissue and to grow

4.  Primary producers (Autotrophs)  use solar energy and elements in soil to make their own nutrients  Consumers (Heterotrophs)  cannot make their own nutrients  they MUST eat other organisms to obtain them: Herbivores: plants Carnivores: meat Omnivores: plants & meat Decomposers: dead/decaying plant & animal matter Parasites: live in/on “host” organism

5.  Used to show how energy flows through ecosystem  As move up each level:  Only 10% energy is available for next level  The # organisms decreases  The Biomass (total weight of living matter) decreases

6.  1. What is a population?  2. Name two factors that effect population.

7.  Only available in fixed amounts  Must be recycled throughout biosphere  Nutrient Cycle: path along which nutrients are passed from one organism to another and from one part of the biosphere to another

8.  1) Water evaporates from earth into atmosphere (water vapor)  2) Water is cooled, and condenses (liquid)  3) Clouds form from water & particles in the air  4) Water falls back to earth as precipitation (rain, snow, etc.)

9.  Nitrogen Fixation: bacteria convert nitrogen in atmosphere to usable form  1) Nitrogen is used to make amino acids (proteins) for plants  2) Heterotrophs eat plants, die, and decompose  3) Nitrogen returned to atmosphere by bacteria and photosynthesis

10.  1) Atmospheric CO 2 is used by plants during photosynthesis  2) CO 2 is produced by all organisms during cellular respiration