Science, 2009
  Grade Level:   9-12  
  EALR 4:   Life Science  
  Big Idea:   Ecosystems (LS2)  
  Core Content:   Maintenance and Stability of Populations                   
  Description:   In prior grades students learned to apply key concepts about ecosystems to understand the interactions among organisms and the nonliving environment. In grades 9-11 students learn about the factors that foster or limit growth of populations within ecosystems and that help to maintain the health of the ecosystem overall. Organisms participate in the cycles of matter and flow of energy to survive and reproduce. Given abundant resources, populations can increase at rapid rates. But living and nonliving factors limit growth, resulting in ecosystems that can remain stable for long periods of time. Understanding the factors that affect populations is important for many societal issues, from decisions about protecting endangered species to questions about how to meet the resource needs of civilization while maintaining the health and sustainability of Earth's ecosystems.  
  Content Standard:   9-11 LS2A Matter cycles and energy flows through living and nonliving components in ecosystems. The transfer of matter and energy is important for maintaining the health and sustainability of an ecosystem.  
Students are expected to:
  • Explain how plants and animals cycle carbon and nitrogen within an ecosystem.
  • Explain how matter cycles and energy flows in ecosystems, resulting in the formation of differing chemical compounds and heat.