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2.2
2.2 – Food Webs and Energy11/6/14 27
LT: Use food webs to explore amounts of energy transferred in an ecosystem.
VOCABULARY – ( see next slide) – Write these down
Procedure – In groups – 1.Example food chain ( use handout)2.Example food web ( use handout)3.Example energy pyramid ( use handout)
Analysis : Attach worksheet
SECTION 2.2VOCAB
trophic level – levels on a food web –
producers= 1st, primary consumers = 2nd,
Calories – unit used to report energy
content in food – kilocalorie = 1000calories
calories = amount of energy required to
raise 1g of water 1° C
food chain – shows flow of energy in organisms
in a linear diagram ( who eats who)
food web – shows all relationships among all
interacting food chains
A. LOOK and IMAGINE! Make a list of at least 10 organisms living in a pond (include micro & macroscopic organisms and plants and animals).
B. Identify each as a producer or consumer.C. Identify consumer as primary, secondary,
and/or tertiary.
POND LIFE
PRODUCER
CONSUMER – primary, secondary, tertiary
PHYTOPLANKTON
ZOOPLANKTON
FLORA
FAUNA
OMNIVORE, HERBIVORE, CARNIVORE
ANY other bold words in book so far
WORDS to KNOW
microscopic
macroscopic
and bacteria
ARROWS: •represent flow of MATTER & ENERGY•point to the eaters!•point to where the energy is going!
veggies humans
phytoplankton zooplankton
Tidal Marsh Web
Create a PosterIn your groups – on your poster – use the handout. Have one member take a picture of your poster after you okay it with Mrs. Kimble. E-mail it to [email protected]
Food Chain
Food Web
Energy Pyramid
Energy Transfers in an Ecosystem
NOTE: only about 10% - 20% of energy is passed to the next trophic level….
the other 80-90% is “lost” to the environment as heat….
Or wasted in undigested food
The sun is the original source of energy, in the form of light, for the food chain.(100,000 Units of Energy)
Plants capture approximately 1% of the available light energy from the sun for biomass production by way of photosynthesis. Photosynthesis can be described chemically as: Light Energy + 6C02 + 6H20 = C6H1206 + 602(1,000 Units of Energy)
Herbivores consume approximately 10% of the plant biomass produced in a typical food chain.(100 Units of Energy)
Carnivores capture and consume about 10% of the energy stored by the herbivores.(10 Units of Energy)
1st trophic level
2nd trophic level
3rd trophic level
4th trophic level
1. Which trophic level consumers must eat the MOST food?
Energy is used much more efficiently if humans eat plants (first tropic level) instead of meat (second tropic level). A given area of farmland can support more people if the crops are fed directly to people rather than to livestock that people then eat.For example if a man needs 3,000 Calories per day, then 30,000 Cal beef are needed, which in turn need 300,000 Cal of corn, which in turn means 30,000,000 Cal of sunshine. This works out to be 1.5 acres of corn per day per person. If the person ate corn directly then 10 people could be supported by the same 1.5 acres of corn.
corn300,000 Cal
corn300,000 Cal
90% energy lost
30,000 Calwhich feeds10 people, ifeach personneeds 3,000 Cal
30,000 Cal feedscows
90% energy lost
3,000 Cal availabefor 1 person!
Food Calories
1 Calorie = 1 kilocalorie = 1,000 energy calories
How are the number of food Calories determined?
*food is burned in a chamber – like “burn a nut”
Why do different foods have different numbers of Calories?
*different chemical composition…. like different kinds of nuts….
protein 4 Cal/g
carbos 4 Cal/g
fats 9 Cal/g
LAW OF CONSERVATION OF ENERGY
Energy cannot be created NOR destroyed;it can only change form.
If you were to weigh all the plants, all the herbivores, and all the carnivores separately, which would weigh most?
80% energy“lost”
80% energy“lost”
80% energy“lost”
What does FOOD do for consumers?*nutrients, like protein*chemicals, that contain ENERGY**
This ENERGY is released during digestion and used to carry out life functions.
Stored chemical energy can also be released as…….
