1. Symbiosis, Food Webs, Limiting Factors SC. 7. L. 17
Symbiosis, Food Webs, Limiting Factors SC.7.L.17.2: Compare and contrast the relationships among organisms, such as mutualism, predation, parasitism, competition, and commensalism. (Also assesses SC.7.L.17.1 and SC.7.L.17.3.) SC.7.L.17.1: Explain and illustrate the roles of and relationships among producers, consumers, and decomposers in the process of energy transfer in a food web. SC.7.L.17.3: Describe and investigate various limiting factors in the local ecosystem and their impact on native populations, including food, shelter, water, space, disease, parasitism, predation, and nesting sites.
Essential Question:
What relationships can exist between organisms in ecosystems and how do organisms interact in order to survive?

2. BellRinger
A fox preys upon a rabbit, and the rabbit feeds on grass. The grass grows through the process of photosynthesis, so it requires sunlight, water, and carbon dioxide. One summer, the Sun shone every day, but there was no rain. How would these weather conditions most likely influence the rabbit and fox populations?
There will be an increase in rabbits and an increase in foxes.
There will be an increase in rabbits and a decrease in foxes.
There will be a decrease in rabbits and an increase in foxes.
There will be a decrease in rabbits and a decrease in foxes.

3. BrainPop
/symbiosis/
As you watch the BrainPop Video on Symbiosis, write down any questions you may have on your sticky notes. If your question is not answered during the lesson, ask it before the “You Do” portion.

4. I Do Guided Notes

5. Types of Symbiotic Relationships
Symbiosis is an interaction between two different organisms that are in the same ecosystem.
Types of symbiotic relationships:
commensalism: one organism benefits while the other is unaffected
parasitism: one organism benefits while the other is harmed
mutualism: both organisms benefit
- website

6. Other Interactions in Ecosystems
Competition: When two or more organisms are trying to use the same limited resource at the same time.
Plants competing for sunlight →
Predation (Predator-Prey): When one organism kills and eats the other for energy and nutrients.

7. Roles in Food Webs
Producers: basis of the food web. Change light energy into food through photosynthesis. Autotrophs (makes own food)
Consumers: Get energy by eating other organisms. Herbivores, carnivores, or omnivores are all heterotrophs (eats others).
Decomposers: get energy by breaking
down dead organisms.

8. Limiting Factors:
Limiting Factors: When there is not enough of one resource that many populations or individuals need.
They create competition and can lead to smaller populations due to organisms leaving the area or dying off.
Not enough Shelter for organisms to live in.
Not enough Water to live in or drink.
Not enough Space, causing crowding.
Because organisms are closer, Diseases can spread easily.
Organisms are forced to Parasitism to survive.
The amount of Food changes if Predation can’t happen.
There are fewer Nesting Sites for organisms to keep their young safe.

9. We Do Collaborative Activity

10. Have students identify producers, consumers, and decomposers in this picture.

11. Revisiting the BellRinger
A fox preys upon a rabbit, and the rabbit feeds on grass. The grass grows through the process of photosynthesis, so it requires sunlight, water, and carbon dioxide. One summer, the Sun shone every day, but there was no rain. How would these weather conditions most likely influence the rabbit and fox populations?
There will be an increase in rabbits and an increase in foxes.
There will be an increase in rabbits and a decrease in foxes.
There will be a decrease in rabbits and an increase in foxes.
There will be a decrease in rabbits and a decrease in foxes.*

12. You Do Time!

13. You Do Question #1
In science class, Eric learns about relationships between organisms in nature. The concepts of predation and parasitism tend to confuse him. Which explains the difference between these two concepts?
Parasitism results in two organisms benefiting instead of only one
Parasitism happens over time, so the organism needs to be a living host
Predation results in one organism being harmed while another benefits
Predation and parasitism are the same thing, since one organism is harmed
CORRECT ANSWER: B

14. You Do Question #2
Sharks are the top predator in a marine ecosystem. By eating them, sharks maintain a balance in the population of smaller organisms. If the shark’s population were to decrease, the smaller organisms would increase greatly, interrupting the food web. Which of the following relationships is MOST similar to the relationship between the shark and the marine ecosystem?
A frog eats flies and lizards in a swamp ecosystem
Leaf-cutter ants eat grass in a prairie ecosystem
A wolf eats small mammals in a forest ecosystem
An owl eats mice and insects in a forest ecosystem
CORRECT ANSWER: C

15. You Do Question #3
Ryan lives in a house near a small lake. In the past few months, he has noticed that there has been very little rainfall due to a drought. He marked a point in the lake by inserting a metal cylinder in the sand. He recorded the water depth in the table.
What would MOST LIKELY take place in the lake ecosystem based on this data?
The fish population would decrease due to competition for food and shelter
The deer population would increase due to increased space for habitats
Trees near the water’s edge will grow twice as fast during the drought
Fish-eating birds would find it more difficult to catch their prey in the lake
CORRECT ANSWER: A

16. EXIT TICKET (Closing):
What relationships can exist between organisms in ecosystems and how do organisms interact in order to survive?