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The action potential arriving at the presynaptic membrane causes the voltage gated calcium ion channels on the presynaptic membrane to open. This causes an influx of calcium ions into the presynaptic neur...

There would be variation in the length of necks in the early giraffe population.

Those who had longer necks would have an advantage for survival as they would be able to reach higher into the trees...

This is a result of natural selection. Natural selection is the result of a barrier, physical such as the ocean or a volanco eruption. This barrier seperates members of a species. One genetic mutation occ...

The process of DNA transcription can be split up into three stages: initiation, elongation and termination.

First, an enzyme called RNA polymerase binds to a certain sequence of bases called the pr...

Proteins are polymers (large molecules) of amino acids joined by peptide bonds. They are formed by condensation reactions, meaning water is a by-product of their formation, and there are different levels....