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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 light e...

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 other...

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 the w...

When it is too cold the hypothalamus in the brain detects it is too cold it sends nerve impulses or electrical signals through the nervous system to targeted areas:erector muscles (don't laugh): are constric...

first something must occur, a change in the external environment (and more rarely within the body). This is known as a stimulus.This stimulus will be picked up or "recepted" by a receptor.The recep...