| A | B |
|---|
| Enzyme | Biological catalyst |
| Substrate | The molecules on which an enzyme acts. |
| Lock and key | A model used to explain why enzymes are specific to a particular reaction |
| photoreceptor | receptor that detects light |
| pH | A measure of acidity or alkalinity |
| thermoreceptor | receptor that detects temperature |
| Effector | Muscle or gland that brings about a response. |
| Central nervous system | The brain and spinal cord |
| Peripheral nervous system | All the nerves that branch out from the spine. |
| Endocrine system | System of glands that produce hormones. |
| Ectotherm | An organism whose bod temperature rises and falls with ambient temperature. |
| Endotherm | an organism that maintains a constant body temperature. |
| Birds and mammals | These are endotherms. |
| Invertebrates, reptiles, fish and amphibians. | These are endotherms. |
| Migration | Moving to a different region to avoid extreme temperatures. |
| Aestivation | "Hibernating" in hot conditions. |
| Vernalisation | Exposure to cold is required in order for the plant produc flowers and seeds. |
