Food Chains/Webs
Investigative Science
Basha High School
Review: Biotic vs. Abiotic
Review: Biotic vs. AbioticBiotic
Plants Animals Fungi Protists Bacteria Organisms
once living
Abiotic sunlight (solar radiation) water
sources/precipitation wind nutrients in soil heat (geothermal) humidity temperature
Food Chain vs. Food Web Food Chain - A single pathway of feeding
in which organisms transfer energy by eating or being eaten.
Food Web – The interrelated food chains in an ecosystem. All the food chains put together in an ecosystem.
Food Web
Producers vs. Consumers Producers (Autotrophs) - make their own
food Consumers (Heterotrophs) - get energy
from consuming producers or other consumers
Producers vs. Autotrophs Producers- capture
energy from sunlight or chemicals and use the energy to produce food.
Autotrophs- make food from their environment Chemoautotrophs Photoautotrophs
They are the same!!!
Types of AutotrophsPhotoautotrophs - get
energy from the sun-by photosynthesis
Chemoautotrophs - get energy without light- by chemosynthesis
Consumers vs. Heterotrophs
Consumers vs. Heterotrophs Consumers are heterotrophs- get energy
from other organisms There are levels of consumers: primary,
secondary, tertiary, quaternary All consumers are heterotrophs!!
Types of Consumers Herbivores- eat only plants Carnivores- eat only animals Omnivores- eat both plants and animals Detritivores- eat waste and dead matter (plants and
animals). They break down the complex compounds of dead and decaying plants and animals to be recycled as nutrients for producers.
Levels in Food Chain/Web Producers – At the bottom of the food chain/web. These are
green plants, algae, or bacteria that communities depend on. They are autotrophs.
Primary Consumers– These are the herbivores. Examples: butterflies, rabbits, mice
*Secondary Consumers – Organisms that feed on primary consumers. Examples: foxes, owls, frogs
*Tertiary Consumers – Organisms that feed on secondary consumers. Examples: snakes, hawks
*Quaternary Consumers – Organisms that feed on tertiary consumers.
Decomposers – Organisms that feed on waste and dead remains of other organisms for energy. Also known as detritivores.
* Depends on food chain within food web!!!
Third Level Consumers
Second Level Consumers
First Level (Primary) Consumers
Energy Flow in an EcosystemEnergy moves in one direction from:
1. the sun or inorganic compounds
2. To autotrophs (producers)
3. To heterotrophs (consumers)
4. Decomposers (detritivores) get energy from waste and decomposing dead organisms
Trophic (Energy) levels Each step in a food chain/web is called a trophic
level. Producers make up the first trophic level Consumers make up the second, third, and higher
trophic levels
Each trophic level depends on the one below for energy
Types of Pyramids Energy Pyramid – shows energy amounts
at each level of the food chain. Biomass Pyramid – shows physical matter
amounts at each level of the food chain.
Energy Pyramid
Only part of the energy stored in one level can be passed to the next- most energy is consumed for life processes (respiration, movement, etc., and heat is given off)
10% Rule - Only 10% of the energy available within one trophic level is transferred to organisms in the next trophic level
Biomass Pyramid Biomass- the total
amount of living tissue within a given trophic level.
A biomass pyramid represents the amount of potential food available for each trophic level in an ecosystem.
Your Challenge… Draw a food web on your dry erase board.
You don’t have to use pictures, you can use just words.
Label producer, primary consumer, secondary consumer, tertiary consumer, detritivore, carnivore, omnivore, herbivore, sun.
Identify the energy trend as you move up the food web.
Trophic Level Questions (Bio Talk)
1. What is the source of energy that enters the food chain?
2. What limits the size of a community?
3. Energy “lost” from a system usually takes what form?
4. What is a trophic level?
5. What percent of energy is passed from one trophic level to the next?
Types of Species InteractionsPredator-prey- one individual captures, kills, and
consumes anotherParasitism- one individual feeds on another; does not
result in the immediate death of the hostMutualism- a symbiotic relationship where both species
benefit from each otherCommensalism- a symbiotic relationship where one
species benefits and the other is not harmed but does not receive any benefit
Competition- some organisms that live in the same place compete for the same limited resource