Module 5.1 Communication and Homeostasis

The need for communication systems

Survival and Activity

<<All living organisms need to maintain a certain limited set of conditions inside their cells, these include:<<

• <<A suitable pH<<
• <<A suitable temperature<<
• <<An aqueous environment that keeps the substrates and products in solution<<
• <<Freedom from toxins and excess inhibitors<<

<<Without these conditions the cells will become inactive and die.<<

<<Multicellular organisms have specialised cells which all rely on each other, meaning they must be able to communicate to coordinate their activities.<<

The Threat from changing environments

Changing external environments

<<External changes may place stress on living organisms.<<

<<For example:<<

• <<Cooler environment causes greater heat loss<<

<<if organism needed to remain active and survive, changes to environment must be monitored and organism must change their behaviour or their physiology to reduce stress.<<

• <<Environmental change= Stimulus<<
• <<Changes in behaviour/ physiology= Response<<

Environment can change slowly as seasons pass- they elicit a gradual response - Example Arctic Fox:

• Has much thicker white coat in winter and a thinner brown/ grey coat in the summer.
• Coat provides greater insulation and camouflage in the winter ensuring the animal can survive and in summer the animal does not overheat.

Environments can also change