Energy Flow in an Ecosystem

1. Energy Flow in an Ecosystem

2. What is an Ecosystem? • An ecological system - consists of a living community and all of the physical aspects of its habitat - physical factors are known as abiotic factors and can include: light, temperature, precipitation, soil type, water availability, soil and water pH, etc… - the members of the living community are known as the biotic factors in an ecosystem - the biotic and abiotic factors in an ecosystem influence each other.

3. Ecosystems and Energy • Ecosystems rely on energy -The amount of energy available in an ecosystem determines how many organisms can live in that ecosystem

4. Energy Source • How does energy enter an ecosystem? - Sunlight is the primary source of energy for most ecosystems on earth No sun = No energy No Energy = No Life No Life = BUMMER!

5. Energy Enters an Ecosytem • Sunlight needs to be converted to be used in an ecosystem. • Who converts the sunlight? - plants, algae, some bacteria - organisms that convert the energy from sunlight into a useable form are known as producers - How do they do convert the energy? Photosynthesis

6. Photosynthesis • Why is it important? - traps the sun’s energy and stores it in a sugar called glucose. - The stored energy is used by living things

7. Photosynthesis Equation 6 CO2 + 6 H2O + Energy C6H12O6 + 6 O2 Carbon WaterSunlight Glucose Oxygen Dioxide

8. Who uses Energy? • Who uses the energy trapped by producers? - All living things use the energy trapped by producers - producers use this energy themselves - Other living things, called consumers eat producers for their energy

9. Cellular Respiration- Using Energy Living things break down glucose and the energy stored in it, using a process called cellular respiration C6H12O6 + 6O2 6CO2 + 6H2O + Energy Glucose Oxygen Carbon Water ATP Dioxide

10. Consumers • Herbivore – plant eater • Carnivore – animal eater • Omnivore – eats both plants and animals

11. Photosynthesis & Respiration • Photosynthesis • 6 CO2 + 6 H2O + Energy C6H12O6 + 6O2 • Cellular Respiration • C6H12O6 + 6O2 6CO2 + 6H2O + Energy • The two processes are the opposite of each other - the products of one process are the reactants of the other

12. Biotic Factors – the Living Part of the Ecosystem • Divided into Trophic (feeding) levels. • Primary producers/autotrophs • Primary consumers/herbivores-plant eaters • Secondary consumers/carnivores –meat eaters • Tertiary consumers/carnivores • Detritivores/decomposers- vital part of the ecosystem. They recycle abiotic materials from dead organisms – without them, life would stop. - they play a role in nutrient cycling

13. Energy Pyramid Tertiary Consumers Secondary Consumers Decomposers Primary Consumers Detritus Feeders Primary Consumers Producers Producers

14. Energy Pyramid

15. Ecological Efficiency • 90% of the energy available is lost as energy is transferred to the next trophic level - the energy is lost as heat • Only 10% is of passed on to the next level (10% Rule) 10 J Snakes 100 J Rats 1,000 J Grasshoppers 10,000 J wheat 100,000 J of sunlight

16. Food Chains • Food Chain – the path of energy through the trophic levels of an ecosystem - all food chains begin with a producer

17. Food Web • Food Web = a series of multiple interconnected food chains. - in most ecosystems, energy doesn’t follow a simple path - many consumers eat at different trophic levels - food webs are a representation of the complex relationships between organisms in an ecosystem

19. Productivity • Productivity is a measure of the amount of energy available in a ecosystem • Gross Primary Productivity: a measure of the total energy captured by plants through photosynthesis • Net Primary Productivity: net primary productivity is the energy available to consumers - the difference between the amount of energy trapped by photosynthesis and the amount used by the plants through cellular respiration

20. Net Primary Productivity - NPP • NPP=GPP-Rs NPP =Net Primary Productivity GPP = Gross Primary Productivity -the total amount of sun’s energy trapped and converted into useable form by photosynthesis Rs= Plant Respiration : - the amount of energy consumed by the plant for its own needs Net Primary Productivity is important because it is the energy available to consumers.

21. Human changes to NPP • 12% decline due to deforestation • Use 28 % used for food, building materials, energy • Together 40% of Earth’s NPP is committed to the use of humans.

22. Vocabulary Abiotic factors Food Chain Biotic Factors Food Web Producers Gross Primary Productivity Consumers Net Primary Productivity Photosynthesis- Definition Photosynthesis – equation Cellular Respiration - Definition Cellular respiration-equation Trophic levels Herbivore Carnivore Omnivore Detritivores/ Decomposers

23. Energy Flow Questions • Most food chains only have 4 levels. Why? • Use your knowledge of energy flow through • an ecosystem to explain why we could feed • more of the Earth’s people by eliminating meat from our diet.