Energy Flow in an Ecosystem Pg. 3-5 Packet 14- Ecology Notes Energy Flow in an Ecosystem Pg. 3-5

Energy Flow All organisms require energy to carry out life processes. Energy can be obtained through various ways according to the type of organism. The sun is the main energy source for life on Earth.

Obtaining Energy Autotroph- (producers) Using energy (such as the sun) to make organic molecules (glucose-food) from inorganic molecules. Auto= Self Troph= To nourish So literally…. It means self nourishing!!

Photosynthesis Converting solar energy into chemical energy (glucose). Examples: plants, algae and some bacteria

Chemosynthesis A process carried out by bacteria in which they produce carbohydrates using inorganic molecules. Example: bacteria that live in remote locations

Obtaining Energy Heterotrophs- (Consumers) organisms that must rely on other organisms for their energy and food supply. Hetero= different Troph= to nourish So literally…. Must get nourishment from a different source!! They are grouped according to what they eat:

Herbivores Eats plants only. Ex: cows and caterpillars

Carnivores Eat meat only. (Example: owls and snakes)

Omnivores Eat meat and plants. (Ex. Bears and humans)

Decomposers Break down organic matter (ex. Fungi and bacteria)

Detrivores Feed on plant and animal remains and other dead matter. Examples: mites, earthworms, snails, crabs

Obtaining Energy Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers).

Cycling of Energy (and Matter) A. Biomass- the total amount of living material (tissue) in an ecosystem.

B. Food Chain- a single pathway of feeding relationships among organisms (energy transfer). The arrow represent the direction of energy flow. A food chain ALWAYS begins with a producer.

C. Food Web Interrelated food chains in an ecosystem. 5 How many food chains can be found in this food web? 5

Trophic Levels Another way of showing the transfer of energy in an ecosystem is in the energy pyramid. The amount of available energy decreases for higher consumers.

D. Trophic Level Indicates the organism’s position in the sequence of energy transfers (it’s place in the food chain)

Energy Pyramid Shows the amount of available energy at each trophic level. There is no limit to the number of trophic levels that a food chain can support but less energy is available as you move to higher trophic levels. Tertiary (3rd) Consumers Energy Decreases Secondary (2nd) Consumers Primary (1st) Consumers Producers

Ten Percent Law Most of the energy consumed in one trophic level is lost in the form of heat. Only a small percentage of energy is actually passed on to the trophic level above it…This is called the Ten Percent Law.

Ten Percent Law 20 kcal 200 kcal 2,000 kcal 20,000 kcal