I. Energy Flow in Ecosystems
a. Organisms cannot survive w/o energy
b. Life Depends on Sun
i. Energy enters ecosystems through plants
1. Via PHOTOSYNTHESIS
a. Solar energy drives chemical rxns that require CO2 & H2O to make CARBOHYDRATES
i. Carbs = energy rich molecules used to carry out life activities
b. 6CO2 + 6H2O + Solar Energy à
C6H12O6 + 6O2
c. Energy stored in plant carbs is transferred to other organisms when eaten
c. Producers to Consumers
i. PRODUCERS
1. Energy directly from sun via
photosynthesis
2. Also known as AUTOTROPHS
a. Self Feeders in Latin
ii. CONSUMERS
1. Organisms which consume other
organisms
2. A.K.A. HETEROTROPHS
a. Other Feeders in Latin
3. Get energy from sun by eating others
4. Categories of consumers…
a. HERBIVORES
i. Eats producers
b. CARNIVORES
i. Eats other consumers
c. OMNIVORES
i. Eats producers & consumers
d. DECOMPOSERS
i. Eats dead organisms & returns nutrients to ecosystem
iii. Energy is transferred in a pattern
1. SUN à PRODUCER à CONSUMER à DECOMPOSER
d. CELLULAR RESPIRATION
i. Consumers break down food consumed into usable energy
ii. Cellular resp. is opposite of photosynthesis
1. C6H12O6 + 6O2 à 6CO2 + 6H2O + ENERGY
e. Energy Transfer
i. As organisms consume each other, energy is transferred
1. More steps removed from the sun, the less original energy is transferred.
ii. Food Chains vs. Food Webs
1. FOOD CHAIN
a. Shows how energy is transferred by consumption
b. Only shows one possibility
2. FOOD WEB
a. Shows multiple possibilities of energy transfer by consumption
b. More like real life
3. TROPHIC LEVELS
a. = Location of organism on a chain/web
b. Each trophic level higher, organisms lose energy as…
i. Heat, Cellular respiration, Body functions
ii. 90% is used & only 10% is transferred to next level
c. PRIMARY PRODUCERS
i. Found at bottom of chain/web
ii. Receives max energy from sun
d. PRIMARY CONSUMERS
i. Feed directly on producers
e. SECONDARY CONSUMERS
i. Feed on 1° Consumers
f. TERTIARY CONSUMERS
i. Feed on 2° consumers
g. Pattern will continue
4. ENERGY PYRAMID
a. Shows a visual of loss of energy for each trophic level
b. Shows why there are less top-level consumers & lots of producers