What is a stimulus?

How do animals increase their chances of survival?

Complete the sentences:
__________ and ___________ are involved in communicating information from one part of an ___________ to another. This makes sure that the activities of different organs are _____________.

Describe the function, structure and location of receptors

Describe the function and location of receptors

Where does cell signalling occur?

Complete the sentences:
The hormonal system works by cells releasing ___________, which travel in the blood and act as ________ to distant cells. Cell-surface receptors allow cells to recognise the chemicals involved in ______ ___________.