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There are four main non-specific defence systems, all of which are immediate and the same for all pathogens (hence 'non-specific).1) skin: it acts as a primary defence mechanism as the dry, dead cells on ...

DNA is: - double stranded- has thymine as a base- longer RNA is:- single stranded- has uracil as a base (instead of thymine)- shorter

Tropism is directional growthPhototropism is directional growth in response to light.Negative phototropism is growing away from the light e.g. in the rootsPositive phototropism is growing towards the ligh...

A change in the environment occurs. Through random mutations already present in the population (this is known as natural variation) certain individuals will be able to cope with the change more so than ot...

The nerve impulse starts at the dendrites, branch like structures,They then travel to the dendrons which make up the length of the neurone between the dendrites and the cell body.The cell body controls th...