Hierarchy of Ecological Relationships
Hierarchy of Ecological Relationships
Objectives
In this unit, students examine various relationships between organisms in ecosystems. Students will:
- apply the concept of trophic levels in ecosystems.
- trace the flow of energy through ecosystems using food chains, food webs, and energy pyramids.
- compare various symbiotic relationships (e.g., predator–prey, parasitism, mutualism, and commensalism).
- examine the effects of human activities on relationships in a coral reef ecosystem.
Essential Questions
Related Unit and Lesson Plans
Related Materials & Resources
The possible inclusion of commercial websites below is not an implied endorsement of their products, which are not free, and are not required for this lesson plan.
- Performance Assessment handout (S-8-9_Shark Performance Assessment and KEY.doc)
- Introduction to Food Chains & Food Webs
Formative Assessment
-
View
Multiple-Choice Items:
Use the food chain below to answer questions 1 and 2.
grass → cricket → sparrow → owl
1. Which organism is the secondary consumer?
A
Grass
B
Cricket
C
Sparrow
D
Owl
2. What would most likely happen if the sparrow population decreased in the community?
A
The crickets would have more grass to eat.
B
The owl population would increase.
C
The cricket population would increase.
D
The grass would grow more slowly.
3. What kind of information is represented by the energy pyramid shown below?
A
The number of different species in an ecosystem
B
The transfer of energy between organisms at each level
C
The amount of matter available at each trophic level
D
Humans have more energy than the pigs or grains
4. Killer whales eat seals. If the seal population declines, the killer whale population also declines. Which of the following best describes the relationship between killer whales and seals?
A
Killer whales are prey of seals.
B
Seals and killer whales are both producers.
C
Killer whales are predators of seals.
D
Seals are competitors with killer whales.
5. A student has two pet frogs, which s/he keeps in a terrarium, along with several types of insects and plants. What level of an ecosystem is represented by all of the organisms in the terrarium together?
A
Community
B
Ecosystem
C
Individuals
D
Population
6. Which group of organisms is independent of other organisms for energy?
A
Decomposers
B
Primary consumers
C
Secondary consumers
D
Producers
7. Based on the data in the table below, which of these statements about the two populations is true?
Population Size of Red Foxes and Rabbits in a State Park from 2005–2009
Year
Number of Red Foxes
Number of Rabbits
2005
79
785
2006
93
728
2007
110
645
2008
91
668
2009
83
691
A
Both populations were largest in 2007.
B
Both populations were smallest in 2005.
C
When the number of red foxes increases, the number of rabbits increases.
D
When the number of red foxes increases, the number of rabbits decreases.
8. In the food web shown below, what is a source of energy for the herbivorous zooplankton?
A
Arctic cod
B
Phytoplankton
C
Carnivorous zooplankton
D
Capelin
9. The presence of fleas living on a dog harms the dog while benefiting the fleas. What type of biological relationship is this?
A
Parasitism
B
Commensalism
C
Mutualism
D
Predation
Multiple-Choice Answer Key:
1. C
2. C
3. B
4. C
5. A
6. D
7. D
8. B
9. A
Short-Answer Items:
10. Give a specific example of a predator and prey, and describe the relationship using the terms energy and trophic level.
11. How have human activities affected coral reef ecosystems, and why is it important to protect coral reefs?
Short-Answer Key and Scoring Rubrics:
10. Give a specific example of a predator and prey, and describe the relationship using the terms energy and trophic level.
Points
Description
2
- Student gives a specific example of a predator and prey relationship.
- Student correctly uses both of the terms energy and trophic level to describe the relationship.
1
- Student explains what predators and prey are, but does not give a specific example.
- Student correctly uses one of the terms energy or trophic level to describe predators and prey.
0
- Student does not correctly explain what predators and prey are or give a specific example.
- Student does not correctly use the terms energy or trophic level to describe predators and prey.
11. How have human activities affected coral reef ecosystems, and why is it important to protect coral reefs?
Points
Description
2
- Student correctly describes at least two effects of humans on coral reef ecosystems.
- Student thoroughly and correctly explains why it is important to protect coral reefs.
1
- Student correctly describes one effect of humans on coral reef ecosystems.
- Student briefly and correctly explains why it is important to protect coral reefs.
0
- Student does not correctly describe any effects of humans on coral reef ecosystems.
- Student does not correctly explain why it is important to protect coral reefs.
Performance Assessment
Should We Protect Sharks?
Using the student handout and worksheet Should We Protect Sharks? (S-8-9_Shark Performance Assessment and KEY.doc), students read about the ecological role that sharks play in Atlantic Ocean ecosystems and the relationships among other organisms that depend on shark populations. Students examine a food chain that includes sharks as the top predators. Then, students study graphs containing population data for sharks and sting rays. Students are asked to answer analysis questions on the written information and data, and then use their findings to decide whether we should protect shark populations.
This task is designed to take students approximately 40–50 minutes to complete.
Objectives:
Students will be able to:
- use evidence to make inferences about population dynamics.
- explain information presented in a variety of formats (i.e., written, graphs, and food chain model).
- trace the flow of energy through an ecosystem.
- describe the role sharks play as top predators in ocean ecosystems.
- explain how human activities affect ocean ecosystems.
You may choose to have students work alone or in small groups to complete the first part of the assessment. This would include the reading, graph analysis, and food chain questions. Have students work alone to write the conclusion paragraph. In advance, make copies of the handout and form group assignments. As an extension, students could research and create a poster about the role of sharks in coral reef ecosystems.
Materials:
- Should We Protect Sharks? handout and worksheet (S-8-9_Shark Performance Assessment and KEY.doc)
- “Predators as Prey: Why Healthy Oceans Need Sharks” (Note: All data and graphs in this activity come from this source.)
Resources:
Performance Assessment Scoring Rubric:Points
Description
5
The student completes all five of the requirements:
- Describes the flow of energy in a food chain accurately.
- Identifies trophic levels and describes relationships within the food chain.
- Analyzes data to infer the relationship between populations.
- Evaluates the impact of humans on the ecosystem.
- Uses evidence to form a judgment about whether to protect shark populations.
4
The student completes four of the requirements:
- Describes the flow of energy in a food chain accurately.
- Identifies trophic levels and describes relationships within the food chain.
- Analyzes data to infer the relationship between populations.
- Evaluates the impact of humans on the ecosystem.
- Uses evidence to form a judgment about whether to protect shark populations.
3
The student completes three of the requirements:
- Describes the flow of energy in a food chain accurately.
- Identifies trophic levels and describes relationships within the food chain.
- Analyzes data to infer the relationship between populations.
- Evaluates the impact of humans on the ecosystem.
- Uses evidence to form a judgment about whether to protect shark populations.
2
The student completes two of the requirements:
- Describes the flow of energy in a food chain accurately.
- Identifies trophic levels and describes relationships within the food chain.
- Analyzes data to infer the relationship between populations.
- Evaluates the impact of humans on the ecosystem.
- Uses evidence to form a judgment about whether to protect shark populations.
1
The student completes one of the requirements:
- Describes the flow of energy in a food chain accurately.
- Identifies trophic levels and describes relationships within the food chain.
- Analyzes data to infer the relationship between populations.
- Evaluates the impact of humans on the ecosystem.
- Uses evidence to form a judgment about whether to protect shark populations.
0
The student demonstrates lack of understanding or does not attempt to complete the assessment.
DRAFT 05/16/2011
