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.