Chapter 3: The Biosphere Section 3-2: Energy Flow
Interest Grabber Pass It Along Section 3-2 • Energy flows in one direction through an ecosystem, from the sun or inorganic compounds to producers (organisms that can make their own food) through various levels to consumers (organisms that rely on other organisms for food). • Your body gets the energy and materials it needs for growth and repair from the foods you eat.
The need for energy… • Energy is needed to drive life processes • Example: Ants can lift many times their mass - energy is needed! • You need energy to wake up! • Ecosystems need energy to sustain life.
A. Producers Sunlight is the main energy source for life on Earth.
A.1:Energy From the Sun • Photosynthesis: Plants harvesting energy from the sun • Convert CO2 & H2O into Carbohydrates & water (Ch 8)
Land Plants are the primary photosynthetic organisms Water Algae or phytoplankton are the main photosynthetic organisms Some photosynthetic bacteria as well Photosynthetic Organisms
Photosynthetic Bacteria • Photosynthetic bacteria like these are found in tidal flats and salt marshes • They are called cynobacteria and contribute to the oxygen on the earth
A-2:Life Without Light: Chemosynthesis • Chemosynthetic bacteria such as these use sulfur in hydrogen sulfide to produce energy rich carbohydrates
Chemosynthetic Bacteria • These bacteria live in remote places on the earth • Yellowstone National Park’s hot springs is one such place • Tidal marshes are another
B. Consumers Heterotrophs: Obtaining energy from producers
Heterotrophs • Organisms that rely on other organisms for energy needs • Also called consumers
Types of Heterotrophs • 1. Herbivores • 2. Carnivores • 3. Detritivores • 4. Decomposers
1. Herbivores • Eat plant material • Examples?
2. Carnivores • Organisms that eat animals • Examples?
3. Omnivores • Organisms that eat both plants and animals • Examples?
4. Detritivores • Organisms that feed on plant & animal remains • They eat dead matter - detritus! • Examples?
C. Feeding Relationships Movement of energy through an ecosystem
Energy Flow • Food - be it plant or animal food - contains energy • Some food contains more energy than others • Energy flows in one direction in an ecosystem
C-1:Food Chains • Energy is passed along in an ecosystem through food chains • Food chain is a series of steps in which organisms pass energy in the form of food
Aquatic Food Chains • Algae/phytoplankton are the basis for the aquatic systems.
Pollution: Disruption in Aquatic Food Chains Biomagnification
C-2: Food Webs • Complex feeding relationships • Feeding relationships can be quite confusing! • This is a Great Lakes food web!
C-3: Trophic Levels • Each step in a food chain is called a trophic level • Produces make up the first level • Consumers make up the 2nd, 3rd etc • Each consumer depends on the trophic level below
D. Ecological Pyramids Representing Energy or the amount of Matter or Numbers in an Ecosystem 3 Types of Pyramids
Section 3-2 Ecological Pyramids Energy Pyramid Shows the relative amount of energy available at each trophic level. Organisms use about 10 percent of this energy for life processes. The rest is lost as heat. Pyramid of Numbers Shows the relative number of individual organisms at each trophic level. Biomass Pyramid Represents the amount of living organic matter at each trophic level. Typically, the greatest biomass is at the base of the pyramid.
D-1: Energy Pyramid • Energy is passed between trophic levels • Organisms use the energy for life functions • Some of the energy is released as heat • 10% is passed on to each successive trophic level
D-2: Biomass Pyramid • Represents the amount of biomass at each trophic level • Expressed in grams / unit area
Biomass Pyramid Enlarged Notice the change in grams @ each successive stage
D-3: Pyramid of Numbers • Represents the number of each organism at each trophic level • May be the same or different than an energy of biomass pyramid