chapter 5.1 energy flow in ecosystems environmental science spring 2011
TRANSCRIPT
Chapter 5.1Chapter 5.1Energy Flow in Ecosystems
Environmental ScienceSpring 2011
OjectivesOjectives
Describe how energy in transferred from the sun to producers and then to consumers
Describe one way in which consumers depend on producers
List two types of consumers Explain how energy transfer in a food web is
more complex than energy transfer in a food cycle
Explain why an energy pyramid is representation of trophic levels
Life Depends on the SunLife Depends on the Sun
Energy from the sun enters an ecosystem when a plant uses sunlight to make sugar molecules in a process called photosynthesis.
Photosynthesis: solar drives a series of chemical reaction thatrequire carbon dioxideand water and produce sugars (carbohydrates).
Life Depends on the SunLife Depends on the Sun
Photosynthesis equatin:
Life Depends on the SunLife Depends on the Sun
Producer: organism that makes its own food◦Ex. Sunflower ◦Also called autotrophs
Consumers: organisms that get their energy from eating other organisms◦Ex. Deer, lion ◦Also called heterotrophs
All organisms get their energy directly or indirectly from the sun!
Life Depends on the SunLife Depends on the Sun
Producer or consumer? Autotroph or heterotroph?
An Exception: Deep-OceanAn Exception: Deep-Ocean
Large communities of worms, clams, crabs, mussels, and barnacles live near deep ocean vents
Exist in total darkness, photosynthesis can not occur
Where do they get energy:◦Bacteria live in some of the organisms and use
hydrogen sulfide to make their own food ◦Bacteria are producers◦Bacteria are eaten by the other underwater
organisms
What Eats What?What Eats What?
Herbivores: consumers that eat only producers ◦Ex. Rabbit, cow, sheep
Carnivores: eat only other consumers ◦Ex. Tiger, wolf, shark
What Eats What?What Eats What?
Omnivores: eat both plants and animals◦Ex. Humans, chimpanzees
Decomposers: consumers get their food by breaking down dead organisms ◦Ex. Bacteria, fungus
Cellular Respiration Cellular Respiration
Cellular Respiration: Process of breaking down food to yield energy◦Cells absorb oxygen and use it to release
energy from food
Cellular Respiration Cellular Respiration
Excess energy you obtain is stored as fat or sugar
All living things use cellular respiration to get the energy they need from food molecules◦Even organisms that make their own food
Energy TransferEnergy Transfer
Each time one organism eats another organism, a transfer of energy occurs
Food chains, food webs, trophic levels ◦Trace transfer of energy
Food Chains and Food WebsFood Chains and Food Webs
Food Chain: a sequence in which energy is transferred from one organisms to the next as each organism eats another organism
Food Chains and Food WebsFood Chains and Food Webs
Food Webs: includes more organisms and multiple food chains linked together, shows many feeding relationships that are possible in an ecosystem
Trophic LevelsTrophic Levels
Trophic Level: each step through which energy is transferred in a food chain
Each time energy is transferred from one organisms to another, some of the energy is lost as heat and less energy is available to organisms at the next tropic level
About 90% of energy at each trophic level is used up, remaining 10% is all that is available to next trophic level
Trophic LevelsTrophic Levels
Energy PyramidsEnergy Pyramids
Each layer represents one tropic level Producers: at base, lowest trophic level,
contains most energy Herbivores: second level, contain less
energyCarnivores: third level, feed on
herbivores, contain less energyCarnivores that feed on carnivores:
highest level, contain less energy
Energy PyramidsEnergy Pyramids
Energy Loss in EcosystemsEnergy Loss in Ecosystems
Because so much energy is lost at each level, there are fewer organisms at the higher trophic levels ◦Ex. 1,000 zebras for every 1 lion on African
savannah ◦Must be enough herbivores to support
carnivores
Energy Loss in EcosytemsEnergy Loss in Ecosytems
Loss of energy from tropic level to trophic level limits the number of trophic levels in an ecosystem
Organisms that feed on organisms at the top trophic level are usually small, such as parasitic worms and fleas that require small amounts of energy