Ecosystems LS 7 Energy flow in an ecosystem

Ecosystems: LS 7

Energy flow in an ecosystem • Ecologists study eating patterns to learn how energy flows within an ecosystem

Energy roles • Each organism has a role in the movement of energy in an ecosystem • This role is called their niche in the ecosystem • An organism can be a – Producer – Consumer – Decomposer

Producers • Energy enters the ecosystem through sunlight • Some organisms use this energy to carry out photosynthesis • These organisms are called producers – They can make their own food • Producers are the source of all food in an ecosystem • Ex: grass and an oak tree are producers for a field ecosystem

Consumers • They obtain energy by feeding on other organisms • They are classified by what they eat – Herbivore • Eat plants only – Carnivore • Eat only animals – Omnivore • Eats both plants and animals – Scavenger • A carnivore that feeds on bodies of dead organisms

Decomposers • Organisms that break down wastes and dead organisms and return the raw material to the environment

Food chain • Energy moves through an ecosystem through a food chain • A series of events in which one organism eats another and obtains energy • The first organism in a food chain is a producer the second is a first level consumer and the third is second level consumer

Food web • A more realistic way to show the flow of energy in an ecosystem • It consists of many overlapping food chains

Energy pyramid • This shows the amount of energy that moves from one feeding level to another in a food web • The organisms at each level use some of the energy to carry out their life processes • The most energy is available at the producer level • The energy pyramid shows interdependence within an ecosystem • At each level in the pyramid, there is less available energy than at the level below – About 10 percent of energy at one level is transferred to the next higher level

Recycling matter • Matter is recycled in an ecosystem • Energy cannot be recycled…it must be constantly supplied (by the sun) • Matter in an ecosystem includes – Water – Oxygen – Carbon – Nitrogen

Water cycle • Continuous process by which water moved from the Earth’s surface to the atmosphere • Evaporation – Molecules of liquid water absorb energy and change to the gas state • Condensation – Gas changes to a liquid • Precipitation – Heavy drops of water that fall to Earth • Rain, snow, sleet, hail http: //teacher. scholastic. com/activities/studyjams/water_cycle/

Carbon and oxygen cycle • Producers take in carbon dioxide through the atmosphere during photosynthesis • They then use this to produce other carbon containing molecules such as sugar and starch • To obtain energy from these molecules consumers break them down and release water and carbon dioxide as waste products • At the same time oxygen is cycled through the atmosphere • Producers release oxygen as a result of photosynthesis • Organisms take in oxygen from the atmosphere and use it for their life processes http: //www. biology. ualberta. ca/facilities/multimedia//uploads/alberta/Carbon. Cycle. ht

Nitrogen cycle • Organisms cannot use nitrogen in the air, they can only use it once it has been “fixed” • Fixed nitrogen – Process of changing nitrogen gas to a usable form – Bacteria does this – These bacteria live in plants known as legumes • Beans, peas, alfalfa, peanuts • Once nitrogen has been fixed it can be used by organism to build protein and other substances • Decomposers break down these complex substances and return it to the soil • Nitrogen is needed to produce amino acids • Nitrogen cycles from the soil to • producers and consumers many times http: //www. sites. ext. vt. edu/virtualfarm/flash_mov/nitrogencycleintro. swf