Post on 27-Mar-2015
Interactions of Living Things Guided Notes
Food Chains, Food Webs, and the Transfer of Energy
GPS: S7L4Students will examine the dependence of organisms on one another and their environments.
Ecology Ecology is the study of the interactions
of living organisms with one another and their environment.
An organism’s environment consists of all the things that affect the organism. Biotic describes living factors in the
environment. Abiotic describes the nonliving part of the
environment, including water, rocks, light, and temperature.
5 Levels of Environmental Organization1st level – Individual organism
any living thing
2nd level – Population a group of organisms of the same species
that live in a specific geographical area
3rd level – Community all the populations of species that live in the
same habitat and interact with each other
5 Levels of Environmental Organization4th level – Ecosystem
a community of organisms and their abiotic environment, such as the rain forest or desert
5th level – Biosphere the part of the Earth where life exists Includes any organism found in the air,
land and water
Autotrophs A group of organisms that can make
their own food by using energy from their surroundings
Autotrophs are also called producers because they produce all of the food that heterotrophs use
Without autotrophs, there would be no life on this planet
Ex. Plants and Algae
AutotrophsChemotrophs
Autotrophs that get their energy from inorganic substances, such as salt
Live deep down in the ocean where there is no sunlight
Ex. Bacteria and Deep Sea Worms
Heterotrophs Organisms that cannot make their
own food
Another term for heterotroph is consumer because they need to consume other organisms to obtain energy and nutrients
Ex. Rabbits, Deer, Mushrooms
HeterotrophsConsumers
1. Scavengers/Detritivores – feed on the tissue of dead organisms (both plants and animals) Ex. – Vultures, Crows, and Shrimp
HeterotrophsConsumers
2. Herbivores – eat ONLY plants Ex. – Cows, Elephants, Giraffes
HeterotrophsConsumers
3. Carnivores – eat ONLY meat Ex. – Lions, Tigers, Sharks
HeterotrophsConsumers
4. Omnivores – eat BOTH plants and animals Ex. – Bears and Humans
HeterotrophsConsumers
5. Decomposers – absorb any dead material and break it down into simple nutrients or fertilizers Ex. – Bacteria and Mushrooms
GPS: S7L4bStudents will explain that in a food web, sunlight is the source of energy and that this energy moves from organism to organism.
Transfer of EnergyThe energy in an organism that is eaten
goes into the body of the organism that eats it
No organism ever receives ALL of the energy from the organism it just ate. For example: When a zebra eats the grass, it does not
obtain all of the energy the grass has (much of it is not eaten)
When a lion eats a zebra, it does not get all of the energy from the zebra (much of it is lost as heat)
Trophic Levels Each step in this transfer of energy is
known as a trophic level The main trophic levels are producers,
consumers, and decomposers
Only 10% of the energy from one trophic level is transferred to the next – this is called the 10% law
GPS: S7L4aStudents will demonstrate that in a food web matter is transferred from one organism to another and can recycle between organisms and their environments.
Food Chains The energy flow from one trophic level to the
next is known as a food chain
A food chain is simple and direct
It involves one organism at each trophic level Primary Consumers – eat autotrophs (producers) Secondary Consumers – eat the primary consumers Tertiary Consumers – eat the secondary consumers Decomposers – bacteria and fungi that break down
dead organisms and recycle the material back into the environment
Food Web In most ecosystems, organisms eat
more than one thing
When more organisms are involved, it is known as a FOOD WEB – a system of many connected food chains in an ecosystem
Food webs are more complex than food chains and involve lots of organisms
Food WebNotice the direction that the arrow points “”, the arrow points in the direction of the energy transfer, NOT “what ate what”
Ecological Pyramid (Energy Pyramid)
An ecological pyramid shows the relationship between consumers and producers at different trophic levels in an ecosystem
Shows the relative amounts of energy or matter contained at each trophic level
The pyramid shows which level has the most energy and the highest number of organisms
GPS: S7L4dStudents will categorize relationships between organisms that are competitive or mutually beneficial.
Types of Interactions There are four main ways that
individuals and populations affect one another in an ecosystem: Competition Predator and prey Symbiosis Coevolution
Types of Interactions Competition happens when more than
one individual or population tries to use the same resources, such as food, water, shelter, or sunlight
Predator-prey interactions occur when one organism eats another to get energy The organism that is eaten is called the
prey, and the organism that eats the prey is called the predator
Types of InteractionsSymbiosis is a close and permanent
association between organisms of different species Commensalism – a relationship in which one
organism benefits and the other is not affected Example: Barnacles on a whale
Mutualism – a relationship in which both organisms benefit from each other Example: Birds eating pest off a rhino’s back
Parasitism – A relationship in which one organism benefits and the other is harmed Example: Ticks on a dog
Types of Interactions Coevolution occurs when a long-term
change happens in two species because of their close relationship
Ex: The relationship between some flowers and the organisms that pollinate them. Flowers need to attract pollinators to help them reproduce. Different flowers have evolved different ways to attract pollinators; some use color or odors, while others use nectar as a food reward.
GPS: S7L4cStudents will recognize that changes in environmental conditions can affect the survival of both individuals and entire species.
Ecological SuccessionA change in the community in which new
populations of organisms gradually replace existing ones 1. Primary Succession – occurs in an area
where there are no existing communities and for some reason (s) a new community of organisms move into the area
Ecological SuccessionA change in the community in which new
populations of organisms gradually replace existing ones 2. Secondary Succession – occurs in an area
where an existing community is partially damaged
Ecological SuccessionA change in the community in which new
populations of organisms gradually replace existing ones 3. Climax Community – a community that is
stable and has a great diversity of organisms
Guided Notes Review1. Differentiate between autotrophs and
heterotrophs. Identify the different types of heterotrophs.
2. Differentiate between a food chain and a food web. Describe how energy travels through a food chain/food web.
3. Describe the structure and organization of an ecological pyramid.
4. Identify and describe the 3 symbiotic relationships.