1. Energy in an ecosystem 6 th grade science 6.l.2.1 and 6.l.2.3

2. Green plants Food provides molecules that serve as fuel and building material for all organisms Plants use the energy from light (sun) to make sugars from carbon dioxide and water. Green plants are the producers of food that is used directly (they eat it) or indirectly (they eat something that eats the plant) by consumers. Plants can use the food they make immediately or store it for later use.

3. Energy flow Energy flows through ecosystems in one direction, from the sun through producers to consumers to decomposers. Water, nitrogen, carbon dioxide, and oxygen are substances cycled between living (biotic) and non-living (abiotic) environments. This is called the carbon cycle.

4. Decomposers Decomposers return nutrients to the environment – such as fungi on fallen logs, mold on bread, and worms in the soil. Bacteria is important because it breaks down dead animals remains when they die This recycles matter in the ecosystem

5. Food webs vs food chains All living things need food to give them the energy to grow and move. A food chain shows how each living thing gets its food. It shows who is eating who. The arrow means "is eaten by". Ex. Grass is eaten by Grasshopper is eaten by Toad is eaten by Snake is eaten by Hawk A food web shows the many different paths plants and animals are connected. Ex: A hawk might also eat a mouse, a squirrel, a frog or some other animal. The snake may eat a beetle, a caterpillar, or some other animal. And so on for all the other animals in the food chain.

7. Energy Pyramid An energy pyramid is a model of energy flow in a community. The different levels represent different groups of organisms that might compose a food chain. From the bottom-up, they are as follows: Producers — bring energy from nonliving sources into the community (highest amount of organisms, contain the most energy) Primary consumers — eat the producers Secondary consumers — eat the primary consumers Tertiary consumers — eat the secondary consumers (least amount of organisms, contain the least energy)

9. Environments The world contains a wide diversity of physical conditions, which creates a wide variety of environments: freshwater, marine, forest, desert, grasslands, mountain, and others In any environment, the growth and survival of organisms depend on the physical conditions.

10. Limiting Factors Environmental factors that affect an organism’s ability to survive in its environment, such as food availability, predators, and temperature are limiting factors A limiting factor is any biotic or abiotic factor that restricts the existence, number, reproduction, or distribution of organisms. Examples – at high elevations, temperatures are low, winds are strong, and soil is thin. Large trees cannot grow here with these factors. Vegetation would have to be small, shallow-rooted plants, mosses, ferns or lichen.

11. Factors that limit one population on a community may also have an indirect effect on another population Example- a lack of water could limit the growth of grass in a grassland reducing the number of seeds produced. The population of rabbits dependent on those seeds for food will also be reduced and the hawks depending on the rabbits will be reduced to as a result of a decrease in their food supply.