1. Define the term "homeostasis".
Answer
Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.
2. List three conditions in the human body that are controlled by homeostasis.
Answer
Blood glucose concentration, body temperature and water levels.
3. What are the two main types of responses of the automatic control systems in the body?
Answer
Nervous and chemical.
4. Name the type of cell that detects stimuli.
Answer
Stimuli are detected by receptor cells.
5. The control systems of the body can involve nervous or chemical responses. Describe the main features that are found in all control systems.
Answer
All control systems have cells called receptors which detect stimuli or changes in the environment. Coordination centres, for example the brain, receive and process information from receptors. Effectors, muscles or glands, then bring about responses which restore optimum levels.
6. One of the conditions controlled in the human body is temperature. Explain why it is important to control body temperature.
Answer
To maintain the optimum temperature for enzyme action.
7. Explain the importance of controlling blood glucose concentration.
Answer
Glucose is needed for respiration to provide the body with energy in the form of ATP.
8. The figure below shows some organs of the human body. Name the organ that produces urea, produces urine and controls body temperature.
Answer
The liver produces urea, the kidneys produce urine, and the skin controls body temperature.