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What is the all or nothing principle?

Basically this means that if the threshold voltage of a neurone is reached -40mV, then a stimulus will be generated of always +40mV. If the threshold is not reached then there will be no signal.

Answered by Katie D. • Biology tutor

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What is speciation?

Speciation is the EVOLUTION of a NEW SPECIES from an EXHISTING SPECIES.

If two populations are seperated so the flow of alleles stops (e.g geographic isolation- a physical barrier that p...

Answered by Katie D. • Biology tutor

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What is sex linkage?

Sex linkage is a type of genetic disease, where the gene with the faulty allele is carried on the X chromosome.

Women have 2X chromosomes whilst men only have 1. Conseque...

Answered by Katie D. • Biology tutor

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What is the difference between an artery and a vein?

Arteries and veins both carry blood around the body, and they each have three main layers of tissue (a ring of endothelial tissue at the centre of the blood vessel surrounded by a layer of muscle and e...

Answered by Emily W. • Biology tutor

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