Home > Subjects > Biology > Level 3 > 3.4 Internal Environments > Key tips
- Subject: Biology
- AS: AS 91604
- Level: 3
- Credits: 3
- Internal
Biology 3.4 Demonstrate understanding of how an animal maintains a stable internal environment
Key tips
Highlight important information in the instructions given to you by your teacher. This will help you to find out things such as:
- what control system you are investigating
- time available and due date of the assessment
- resources that are available for you to use
- format of the report.
The difference between achieved, merit and excellence is in depth of understanding you show about the control system you are investigating. For achieved you are expected to describe the control system – its purpose, its component parts and how it works to maintain a stable internal environment eg stable temperature, stable blood pressure, stable level of glucose.
For merit you are expected to explain how or why the control system works to maintain a stable internal environment and explaining how the control system re-establishes a stable internal environment after a specific disruption occurs eg when exercising the body temperature rises (this is a specific disruption) and the control system must return the body temperature to normal.
For excellent you are expected to link biological ideas to show comprehensive understanding of how or why the control system works to maintain a stable internal environment, including ONE of the following:
- adaptive advantage of the control system.
- biochemical and/biophysical processes involved in the working of the control system.
- potential effect of disruption to the system by a specific internal or external influence - such as extreme environment conditions, disease or infection, drugs or toxins, or internal influences such as genetic conditions or metabolic disorders.

