1. Interactions of Living Things Guided Notes
Food Chains, Food Webs, and the Transfer of Energy

2. GPS: S7L4
Students will examine the dependence of organisms on one another and their environments.

3. 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.

4. 5 Levels of Environmental Organization
1st 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. 5 Levels of Environmental Organization
4th 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

6. 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

7. Autotrophs Chemotrophs
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

8. 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

9. Heterotrophs Consumers
1. Scavengers/Detritivores – feed on the tissue of dead organisms (both plants and animals)
Ex. – Vultures, Crows, and Shrimp

10. Heterotrophs Consumers 2. Herbivores – eat ONLY plants
Ex. – Cows, Elephants, Giraffes

11. Heterotrophs Consumers 3. Carnivores – eat ONLY meat
Ex. – Lions, Tigers, Sharks

12. Heterotrophs Consumers 4. Omnivores – eat BOTH plants and animals
Ex. – Bears and Humans

13. Heterotrophs Consumers
5. Decomposers – absorb any dead material and break it down into simple nutrients or fertilizers
Ex. – Bacteria and Mushrooms

14. GPS: S7L4b
Students will explain that in a food web, sunlight is the source of energy and that this energy moves from organism to organism.

15. Transfer of Energy
The 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)

16. 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

17. GPS: S7L4a
Students will demonstrate that in a food web matter is transferred from one organism to another and can recycle between organisms and their environments.

18. 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

19. 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

20. Food Web
Notice the direction that the arrow points “”, the arrow points in the direction of the energy transfer, NOT “what ate what”

21. 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

22. GPS: S7L4d
Students will categorize relationships between organisms that are competitive or mutually beneficial.

23. Types of Interactions
There are four main ways that individuals and populations affect one another in an ecosystem:
Competition
Predator and prey
Symbiosis
Coevolution

24. 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

25. Types of Interactions
Symbiosis 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

26. 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.

27. GPS: S7L4c
Students will recognize that changes in environmental conditions can affect the survival of both individuals and entire species.

28. Ecological Succession
A 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

29. Ecological Succession
A 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

30. Ecological Succession
A 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

31. Guided Notes Review
Differentiate between autotrophs and heterotrophs. Identify the different types of heterotrophs.
Differentiate between a food chain and a food web. Describe how energy travels through a food chain/food web.
Describe the structure and organization of an ecological pyramid.
Identify and describe the 3 symbiotic relationships.