Physiological Responses in Ectotherms
Physiological adaptations include colour. Dark colours absorb more radiation. The Namaqua chamelion is black in the morning but pale grey during the hotter day.
Ectotherms have much lower metabolic rates than ectotherms and the metabolic rate rises with the ambient temperature since the rate of enzyme action is directly related to temperature.

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Key terms in this lesson
- Ectotherm
- An organism that relies mainly on external sources of heat to regulate its body temperature.
More in Homeostasis
- Feedback Systems
- Examples of Positive Feedback
- Endotherms and Ectotherms
- Behavioural Responses in Ectotherms
- Thermoreceptors
- The Hypothalamus
- Cooling
- Warming Up
All 33 lessons in Homeostasis · All OCR A-level Biology topics