Cell Signalling

Organisms can sense what is around them in their environment. This allows them to make changes or respond appropriately to changes, like an increase in nutrients.

An Amoeba detects nutrients around it in the water. It moves towards the nutrients and takes them into the cells. If the Amoeba couldnt do this it would be unable to get nutrients and therefore unable to live or survive.

Cells have to coordinate themselves to be able to detect internal and external signals and respond appropriately. To detect signals cells have ''sensors'' on their surface known as receptors. They're usually proteins or modified proteins. 

Hormones

Hormones are produced specifically for cell communication. They're made for target cells - any cell with receptors. The hormone binds to…