Energy in Food Chains

B. ENERGY:B. ENERGY: THERMODYNAMICSTHERMODYNAMICS

1st Law energy can neither be created nor destroyed it

merely changes form solar chemical mechanical heat

2nd Lawevery time energy changes form some energy is lost as “waste” or useless energy in the form of heat (less energy at the end of the transfer than at the beginning)

Living things and the cells that make them up must follow the laws of thermodynamics. Cells take energy and convert it into different forms.Important principles in biology that govern the chemical process of metabolism

ENERGY: THE SUNENERGY: THE SUN source of all energy for living organisms absorbed or reflected by:

gases in the airwater (clouds, ice, lakes, etc…)rocks and soilliving organisms

photosynthesiscollect solar energyconvert to chemical energy (food)

ENERGY: PHOTOSYNTHESISENERGY: PHOTOSYNTHESIS green plants (some single celled organisms) collect sunlight

using a green pigment called chlorophyll plants convert light, CO2 and water to glucose (sugar)

plants serves as the origin of food for all other organisms:

directly from herbivores eating green plants

indirectly from other animals (carnivores) eating the herbivores

ENERGY IN FOOD CHAINSENERGY IN FOOD CHAINS

producer primary (1o)consumer

secondary (2o)consumer

10%

90% 90%

energy used to live

energy passed to consumer

10% Rule: only 10% of the energy in an organism is stored and passed on to the next trophic level (90% of the energy is used to live).

10%

ENERGY IN ECOSYSTEMS & TROPHIC LEVELS

The term trophic level describes the place in a food chain that an organism feeds

1st TROPHIC LEVEL

• producers or autotrophs that feed themselves

2nd TROPHIC LEVEL

herbivores or primary [1o] consumers that eat producers

3rd TROPHIC LEVEL

carnivores or secondary [2o] consumers that eat herbivores

4th TROPHIC LEVEL

carnivore or tertiary [3o] consumers that generally eat other carnivores

All consumers are called heterotrophs.

All producers are called autotrophs

A food web is a series of interconnected food chains

HAWK

WEASEL

BOBCAT

MOUSE

GRASSHOPPER

FROG

SEEDS GRASS

VOLE

FALLEN LEAVES

BACTERIA

HAWK

WEASEL

BOBCAT

MOUSE

GRASSHOPPER

FROG

SEEDS GRASS

VOLE

FALLEN LEAVES

Identify an autotroph

Identify a primary consumer

produces its own food

eats a producer (herbivore)

BACTERIA

HAWK

WEASEL

BOBCAT

MOUSE

GRASSHOPPER

FROG

SEEDS GRASS

VOLE

FALLEN LEAVES

Identify a secondary consumer

a carnivore that eats other herbivores

producer

1o consumer

2o consumer

BACTERIA

HAWK

WEASEL

BOBCAT

MOUSE

GRASSHOPPER

FROG

SEEDS GRASS

VOLE

FALLEN LEAVES

Identify an organism at the fourth trophic level

BACTERIA

HAWK

WEASEL

BOBCAT

MOUSE

GRASSHOPPER

FROG

SEEDS GRASS

VOLE

FALLEN LEAVES

Identify a decomposer something that eats dead things

Identify an omnivore something that eats plants & animals

BACTERIA

HAWK

WEASEL

BOBCAT

MOUSE

GRASSHOPPER

FROG

SEEDS GRASS

VOLE

FALLEN LEAVES

Explain what would be the effect on voles of fewer hawks

hawks = weasels and mice

mice & weasels = grasshoppers

grasshoppers = grass

grass = food for voles = voles

BACTERIA

HAWK

WEASEL

BOBCAT

MOUSE

GRASSHOPPER

FROG

SEEDS GRASS

VOLE

FALLEN LEAVESExplain what would be the effect on bobcats of fewer grasshoppers

OVER THE SHORT TERM

grasshoppers = grass & seeds = food for frog, weasels & mice

food for frogs means frogs leave or die

frogs means less food for bobcats = bobcatsOVER THE LONG TERM

grass = more food for voles = voles

voles = more food for bobcats = bobcats

BACTERIA

HAWK

WEASEL

BOBCAT

MOUSE

GRASSHOPPER

FROG

SEEDS GRASS

VOLE

FALLEN LEAVES

Explain, what would be the effect on grasshoppers of fewer leaves

fallen leaves = food for voles

voles now eat more grass

grass for grasshoppers = grasshoppers

(they die off/ or leave area as less food)

food means some voles leave

voles = food for bobcat

bobcats now eat more frogs

frogs = weasels eat more grasshoppers

fewer grasshoppers

BACTERIA

OVER THE SHORT TERMOVER THE LONG TERM

HAWK

WEASEL

BOBCAT

MOUSE

GRASSHOPPER

FROG

SEEDS GRASS

VOLE

FALLEN LEAVES

Explain what would be the effect on hawk of fewer bobcats.

bobcats = voles and frogs

frogs = food for weasels

some weasels leave or die off = food for hawks

= fewer hawks

OVER THE LONG TERM

voles eat more grass = grass

grass for grasshoppers & mice

grasshoppers & mice

= food for hawks fewer hawks

BACTERIA

OVER THE SHORT TERM