Clarification details
Updated July 2014. This clarification has been updated to address issues that have arisen from moderation.
Intent
The intent is for students to demonstrate understanding within a single control system in an animal, including humans. The focus is on the internal control processes for maintaining a stable internal environment (homeostasis) despite external fluctuation. This gives opportunity to further explore systems thinking in a biology context. It recognises that systems may be complex, yet understood, using a systems approach.
Achieved
Understanding involves the student using biological ideas to describe the control system. This includes a description of how balance is re-established following a potential disruption to this homeostatic system by internal or external influences, for example by describing how the system responds to the normal range of environmental fluctuations rather than by providing a complete breakdown of the system.
Merit
In-depth understanding involves the student using biological ideas to explain how or why an animal maintains a stable internal environment. This includes explaining how a specific disruption results in responses within the control system to re-establish a stable internal environment. For example, by explaining the way the system responds to the normal range of environmental fluctuations rather than a complete breakdown of the system.
Excellence
Comprehensive understanding involves the student linking biological ideas about maintaining a stable internal environment in an animal. This may include an analysis of a specific example of how external and/or internal environmental influences result in a complete breakdown of the control system.
Biological ideas
Because this is a new standard there is added detail in the explanatory notes to clarify the intended scope of biological ideas. Those related to the control system are listed in Explanatory Note 4. Environmental influences that may result in a breakdown of the control system are listed in Explanatory Note 5.
Control systems (i.e. homeostatic systems)
Control systems maintain a stable internal environment and refer to one of those chosen from the list in Explanatory Note 3. Systems studied by students will vary between (and possibly within) schools in response to interest, expertise and opportunity.