Cell differentiation

Animals and plants produced by sexual reproduction begin life as a single cell - a fertilised egg or zygote.

This cell must divide to produce a multicellular organism. It must also differentiate, so that its cells develop features that enable them to fulfil specific roles.

Examples in animals include:

Cells of the…Specialised to…
Circulatory systemTransport substances, defend the body, regulate temperature
Excretory systemRemove waste products and unwanted substances, regulate the water content of the body
Muscular systemBring about movement
Nervous systemRespond to internal and external stimuli and conditions, carry messages for the body, work as a coordinated whole
Respiratory systemDeliver oxygen for respiration and remove wastes
Reproductive systemBring about fertilisation to produce new offspring
Skeletal systemBring about movement, support and protect internal structures, produce blood cells, store and release calcium

Some specialised cells of plants:

Cells of the…Specialised to…
LeafPalisade mesophyllCarry out photosynthesis
Spongy mesophyllAllow gases to circulate for the exchange of gases between the leaf and the environment, carry out some photosynthesis
Guard cellsOpen and close to control the exchange of gases – carbon dioxide, water vapour and oxygen
PhloemSieve tubesTransport products of photosynthesis, including sugars and amino acids, from the leaf to where they are needed
Companion cellsProvide the energy required for transporting substances in sieve tubes
XylemXylem vesselsTransport water and dissolved minerals from the roots, up the plant
Growing pointsMeristemProduce new cells as they divide