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Big Idea
Ecosystems are ever changing because of the interdependence of organisms of the same or different species and the nonliving elements of the environment.  Seeking matter and energy resources to sustain life, organisms in an ecosystem interact with one another in complex feeding hierarchies of producers, consumers, and decomposers, which together represent a food web.  Ecosystems have carrying capacities that limit the number of organisms they can support.  Individual survival and population sizes depend on such factors as predation, disease, availability of resources, and parameters of the physical environment.  Organisms rely on physical factors, such as light, temp, water, soil, and space for shelter and reproduction.  Within any one ecosystem, the biotic interactions between organisms further influence their growth, survival, and reproduction, both individually and in terms of their populations (A Framework for K-12 Science Education LS2.A).
Essential Questions
What would happen to a population if their resources were continuous and never ran out?
How can abiotic factors affect the growth of populations?
How do abiotic and biotic factors limit population sizes?

Formulate questions based on observations that lead to the development of a hypothesis.
Explain how organisms obtain and use resources to develop and thrive in
  • niches
  • predator/prey relationships
Analyze the interactions of living organisms with their ecosystems
  • limiting factors
  • carrying capacity
Compare food chains in a specified ecosystem and their corresponding food web.
Analyze data to determine how the milkweed population would grow if unlimited. Analyze data to determine how the milkweed population would grow if limited.
Science & Engineering Practices
Using Mathematics and Computational Thinking
Analyzing and Interpreting Data:  students analyze data and draw conclusions
Analyzing and Interpreting Data: students analyze data and draw conclusions about Mono Lake
Content/Core Ideas
  • Reproductive potential is the theoretical growth of a population over time.
  • A limiting factor is any biotic or abiotic component of the ecosystem that controls the size of a populatio.
  • Discuss how biotic and abiotic factors in an environment can limit a population. Explain the roles of both lab experimentation and field observation in the study of populations. Describe the population fluctuations in Mono Lake in terms of limiting factors and feeding relationships.
Crosscutting Concepts
Cause and Effect
Stability and Change
Learning Practices
CC:7.W.1  students write Results and Conclusions on the Milk-weed Bug Hatching Analysis
CC:7.W.1  students use evidence and reasoning to write Conclusions of the Algae and Brine Shrimp Experiment
Academic Vocabulary
  • reproductive potential
  • limiting factor
Mid-summative Exam 6
Milk-weed Bug Hatching Analysis
Milk-weed Bug Reproductive Potential
Algae and Brine Shrimp Analysis
Analysis of Mono Lake