Name: ____________________________________________________
Unit 2: Ecology Study Guide
Date: ______________
4.1.A.a Explain the nature of interactions between organisms in predator/prey relationships and different symbiotic
relationships
-Predator/prey: one organism hunts and feeds on
another
- Mutualism: both species benefit (+,+)
-Commensalism: one species benefits and the other is neither helped nor
harmed (+, 0)
- Parasitism: one species benefits while living on or in a host that is harmed
(+,-)
- Practice: Give an example of each:
1. Predation: _________________________________________________________________________________
2. Mutualism: ________________________________________________________________________________
3. Commensalism: ____________________________________________________________________________
4. Parasitism: ________________________________________________________________________________
4.1.A.b Explain how cooperative (e.g., symbiotic) and competitive (e.g., predator/prey) relationships help maintain
balance within an ecosystem
-If an organism has no predators it will grow rapidly until it reaches carrying capacity
- If an organism has no prey (food) it will die
- If organisms depend on each other (mutualism) and one is harmed, the other will likely be harmed as well
Practice:
5. If a disease kills of all of the rabbits in an area, what will happen to the snakes (their predators)? Why?_____________
__________________________________________________________________________________________________
6. If all the trees in an area are cut down and the owls have nowhere to live, what will happen to the mice (their prey)?
Why? _____________________________________________________________________________________________
__________________________________________________________________________________________________
7. If all the bees in an ecosystem died off, what would most likely happen to the flowers? Why? ____________________
__________________________________________________________________________________________________
4.1.B.a Identify and explain the limiting factors (biotic and abiotic) that may affect the carrying capacity of a
population within an ecosystem
Biotic = Living or once was living
Examples: food, cooperating species, predators
Abiotic = Not living
Examples: space, weather, water, disease, natural disasters
- Carrying capacity = maximum number of individuals that can live in an area
Practice:
8. Explain why predators are a limiting factor: _____________________________________________________________
__________________________________________________________________________________________________
9. Give an example of a natural disaster and explain how that could be a limiting factor: __________________________
__________________________________________________________________________________________________
4.1.B.b Predict how populations within an ecosystem may change in number and/or structure in response to
hypothesized changes in biotic and/or abiotic factors
- Populations increase with births, immigration, abundant food, water, space and few predators
- Populations decrease with deaths, emigration, lack of food, water, space and too many predators
- Populations cannot increase without limits; eventually they will stabilize or even decrease
Practice:
10. What would happen to a population of fish if the lake they were living in became polluted? Why?________________
__________________________________________________________________________________________________
11. If a forest fire burned down a forest, what would happen to the organisms that lived there? Be specific!___________
__________________________________________________________________________________________________
4.2.A.a Illustrate and describe the flow of energy within a food web
- Energy flows in ONE direction
- Arrows show the transfer of energy and always point to the organism that is receiving the
energy.
- Each step in the food web is called a trophic level.
Practice:
12. True/False: If the food chain is correct, circle true. If the food chain is incorrect circle false AND correct it.
a. Snakefroggrasshopperplant
True/False_____________________________________________________________________
b. Crocodile  Water PlantFish Water bug
True/False_____________________________________________________________________
c. Flower beemouseowl
True/False_____________________________________________________________________
13. Create your own food web using all of the organisms in the chart below. If you are unsure of what each animal eats,
use the chart to help you.
Organism
Snail
Fish
Water Bug
Water Plants
Tadpoles
Frogs
Snake
Type of
Heterotroph
Herbivore
Carnivore
Herbivore
Producer
Omnivore
Carnivore
Carnivore
14. What organisms in your
food web are in trophic
level 2?
_______________________
_______________________
15. Which of the following pathways of energy flow would give the final consumer the smallest percentage of original
energy available in a food chain? Explain why.
a. Grass  grasshopper  frog  snake  hawk
b. Grass  mouse  wolf
Food Chain: _____ Why: ____________________________________________________________________________
16. Select a three or 4 link food chain from the above food web. Write it on the line
__________________________________________________________________________________________________
17. Using the food chain you created above, create an energy pyramid below.
4.2.A.c Predict how the use and flow of energy will be altered due to changes in a food web
- The stability of all food webs depends on the amount of producers there are in that ecosystem.
- Organisms may have multiple feeding relationships within a food web
- If one organism is removed a negative “domino effect” will occur with the remaining organisms
- About 10% of the energy available at one trophic level is available to the next
Practice:
18. What would most likely happen in this food web if the rabbits had fewer 0fffspring?
_____________________________________________________________________
____________________________________________________________________
19. What would most likely happen in this food web if the berry tree became extinct?
_____________________________________________________________________
_____________________________________________________________________
4.2.B.b Explain the importance of the recycling of nitrogen, oxygen, and carbon within an ecosystem
-Humans put carbon in the air through respiration and combustion
- Pollution and overuse of natural resources can alter biogeochemical resources
Practice:
21. A plant converts carbon dioxide from the air into material that becomes part of that plant’s structure. How does that
carbon return to humans? ____________________________________________________________________________
22. List two roles that humans perform in the carbon cycle: _________________________________________________
__________________________________________________________________________________________________
Scientific Processes:
23. REMEMBER YOUR LABELS!! (Check your notes if you forgot!)
Fox Population
Rabbit Population
January
5
20
Fox and Rabbit Population
February
March
7
12
16
12
24. Explain the relationship in the graph shown above.
25. Why are the rabbits declining?
April
15
9
May
18
4