Biology I Notes Name:________________________________Date: ______________

Period:______Unit 2: Energy Flow Through Ecosystems

Ecosystem-__________________________________________________________________________________________________

________________________________________________________________________________________________________________

A combination of biotic (_____________________) and abiotic (__________________________) factors

Part 1: Food Chains

Every organism has a niche—_____________________________________________________________________o Includes both physical environment and its mode of nutrition.

2 Modes of Nutrition:

1) Autotroph or Producer— _____________________________________________________________________

o Through either photosynthesis or chemosynthesis

o Photosynthesis—__________________________________________________________________________

o ______________________________________________________________

o Chemosynthesis—_______________________________________

______________________________________________________________

______________________________________________________________

2) Heterotroph—________________________________________________

A) Consumers (eat their food)

i.) Herbivore—_________________________________________

ex: __________________________________

ii.) Carnivore—_________________________________________

Ex: _________________________________

iii.) Omnivore—__________________________________________

Ex: _________________________________

B) Detritivore—_________________________________________________

Ex: _________________________________________

C) Decomposer—_______________________________________________

Ex: _________________________________________

*Key Idea: Energy flows through an ecosystem in one

direction, from the sun to the ____________________ to the

____________________ to the ____________________. Along the way

chemical energy gets degraded into heat that is lost to the

atmosphere and can’t be used by organisms, or released as

waste.

Food Chain:______________________________________________________

____________________________________________________________________

____________________________________________________________________

● Each organism or link in the food chain is called a

______________________ or feeding level.

● Food chains usually have 2-5 trophic levels.

● Arrows always point to the consumer that is

receiving the energy.

Trophic Levels of a Food Chain

1) The _______________________, or autotroph, occupies the _________ trophic level

o Ex: __________________________________________

2) The _______________________, or the consumer that eats the producer, occupies the __________trophic level

o Ex: ___________________________________________

3) The ________________________________, or the consumer that eats the primary consumer,occupies the ________ trophic level in the food chain.

o Ex.: __________________________________________

4) The _______________________, or the consumer that eats the secondary consumer, occupiesthe ________ trophic level in the food chain

o Ex: __________________________________________

5) The _______________________, or the consumer that eats the tertiary consumer, occupies the________ trophic level in the food chain.

o Ex: ________________________________________

Part 2: Food Webs

Food Web:___________________________________________________________________________________________________

Food webs take into consideration the varied diets of organisms.

Why do food chains typically have 5 or fewer trophic levels? __________________________________

________________________________________________________________________________________________________

________________________________________________________________________________________________________

Rule of 10%

● Only 10% of the energy taken in by an organism is used for growth. The energy is stored in the new tissues that can be gained by a consumer.

● The remaining 90% is used in chemical reactions and lost as heat or remains in undigested food waste.

Pyramid of Energy: _______________________________________________________________________________________

● Label the trophic levels and record the amount of energy received by each one.

● The amount of energy available to each trophic level decreases as you move up the food chain. This is because an organism uses most of the energy it takes in or loses it as heat. It only stores 10%, which is available to the consumer.

Pyramid of Numbers _______________________________________________________________

Pyramid of Biomass ________________________________________________________________

● Both of these pyramids may not always have a larger base. ● Top consumers have to eat a lot of organisms from the trophic level below it to get enough

energy to survive. ● Because of this great need to eat, each level can support fewer individuals with an overall

lower mass.

Part 3: Problems in the Food Chain

Biological Magnification- ___________________________________________________________

_______________________________________________________________________

● Chemicals are stored in the fat of animals, so the consumer obtains the chemicals when it eats these animals.

● For example, the pesticide DDT was widely used 1970s. It washed into waterways, where it was stored in the fat of fish. Bald eagles consumed these fish and acquired large amounts of pesticides. These pesticides cause the eagle’s eggshells to thin. As a result, mother birds accidentally crushed their eggs. Bald eagle populations declined, and it became an endangered species.