Nutrition and Energy Flow

1. Nutrition and Energy Flow Ch 2 Section 2 pp. 44-50

2. Energy • All life needs energy to survive • One of the most important characteristics of a species’ niche is how it obtains energy. • Ultimate source of energy comes from the __________! • Plants use the sun’s energy to manufacture food in a process called _______________.

3. Producers or AUTOTROPHS • An organism that uses light energy or other forms of energy to make energy-rich compounds (or their own food) is a producer, or autotroph.

4. Heterotrophs Consume Producers and Other Consumers • Other organisms in the biosphere depend on autotrophs for nutrients and energy. These dependent organisms are called consumers OR HETEROTROPHS. • Consumers cannot use the sun’s energy directly like producers • CONSUMERS MUST CONSUME OR EAT PRODUCERS OR OTHER CONSUMERS • Types of consumers • Herbivore • Carnivore • Omnivore • Scavengers and Decomposers

5. Heterotrophs: Scavengers • Scavengers eat animals that have already died.

6. Heterotrophs: Decomposers • Some organisms, such as bacteria and fungi, are decomposers. • Decomposers break down dead and decaying plants and animals into simpler molecules that can be more easily used by other organisms. • THEY RECYCLE MATERIALS!

7. Food chains: Pathways for matter and energy • A food chain is a simple model that scientists use to show how matter and energy move through an ecosystem. • In a food chain, nutrients and energy (food) move from autotrophs to heterotrophs and, eventually, to decomposers. • USE DIAGRAM ON NEXT PAGE TO CONSTRUCT A FOOD CHAIN • The amount of energy remaining in the final transfer is only a portion of what was available at the first transfer. • A portion of the energy is given off as heat at each transfer.

9. Trophic Levels and Food Chains • Each organism in a food chain represents a feeding step, or trophic level, in the passage of energy and materials. TROPHIC LEVELS ARE LIKE LINKS IN A FEEDING CHAIN! • A first order heterotroph (PRIMARY CONSUMER) is an organism that feeds on plants, such as a grasshopper. • A second order heterotroph (SECONDARY CONSUMER) is an organism that feeds on a first order heterotroph. • A third order heterotroph (TERTIARY CONSUMER) feeds on second order heterotrophs

11. Simple Food Chains • A food chain is drawn using arrows to indicate the direction in which energy is transferred from one organism to the next. • HOW MANY TROPHIC LEVELS OR FEEDING STEPS ARE THERE? berries → mice → black bear

12. Food Webs • A food chain represents only one possible route for the transfer of matter and energy through an ecosystem. • A food web, shows all the possible feeding relationships at each trophic level in a community.

13. Chihuahuan raven Honey mesquite (pods eaten by beetles) Food webs Pronghorn antelope Gambel quail Jackrabbit Desert tortoise Coyote (top carnivore) Prickly pear cactus Long-tail weasel Roadrunner Kangaroo rat (seed eater) Mojave rattlesnake ants Red spotted toad Mexican whiptail lizard Texas horned lizard Section 2.2 Summary – pages 46 - 57

14. Section 2.2 Summary – pages 46 - 57 Energy and trophic levels: Ecological pyramids • An ecological pyramid can show how energy flows through an ecosystem. • The base of the ecological pyramid represents the autotrophs, or first trophic level. Higher trophic levels are layered on top of one another.

15. Section 2.2 Summary – pages 46 - 57 Energy and trophic levels: Ecological pyramids Pyramid of Energy Heat 0.1% Consumers • The pyramid of energy illustrates that the amount of available energy decreases at each succeeding trophic level. 1% Consumers Heat 10% Consumers Heat 100% Producers Heat Parasites, scavengers, and decomposers feed at each level.

16. Section 2.2 Summary – pages 46 - 57 Energy and trophic levels: Ecological pyramids • The total energy transfer from one trophic level to the next is only about ten percent because organisms fail to capture and eat all the food energy available at the trophic level below them.

17. Section 2.2 Summary – pages 46 - 57 Energy and trophic levels: Ecological pyramids • Some of the energy transferred at each successive trophic level enters the environment as heat, but the total amount of energy remains the same.

18. Section 2.2 Summary – pages 46 - 57 Energy and trophic levels: Ecological pyramids • A pyramid of numbers shows that population sizes decrease at each higher trophic level. Pyramid of Numbers Fox (1) Birds (25) Grasshoppers (250) Grasses (3000)

19. Section 2.2 Summary – pages 46 - 57 Energy and trophic levels: Ecological pyramids • Biomass is the total weight of living matter at each trophic level. A pyramid of biomass represents the total weight of living material available at each trophic level. Pyramid of Biomass 1 kilogram of human tissue 10 kilograms of beef 100 kilograms of grain

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22. The Nitrogen Cycle To return to the chapter summary click escape or close this document.

23. The Carbon Cycle To return to the chapter summary click escape or close this document.

24. The Water Cycle To return to the chapter summary click escape or close this document.