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Synapses are the junctions between neurons. An electrical impulse travels down the first neuron and arrives at the presynaptic membrane. The presence of an electrical impulse causes chemicals called neuro...

The cellular structure of the brain is a relatively recent discovery and it's Santiago Ramòn y Cajal that recognised it; in addition to this he recognised the neuron as the basic unit. Three main elements...

Acid in stomach kills pathogens in food.Skin creates a barrier that microorganisms cannot enter through.Hairs in nose and ears that trap microorganisms.Mucus and cilia in the trachea and bronchi that trap...

You need to have some basic knowledge of nucleotide structure before trying to understand the answer below. First of all, DNA contains thousands of genes. Each gene codes for specific proteins (The ‘code’...

They both change the allele frequency, and both select against less well adapted phenotypes. Extremes are eliminated in stabilising selection, whereas intermediates are eliminated in disruptive selection....