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There are two main reasons that smoking can increase blood pressure: Cigarette smoke contains nicotine which, once inhaled, can enter the bloodstream and cause the release of adrenaline which increases the h...

Fish use specialised surfaces called gills to carry out gas exchange. Gills are highly folded, giving them a large surface area and maximising the efficiency of gas exchange. The gill filaments have many pro...

Reproductive separation occurs, this could be through geographical separation . (1) Therefore no interbreeding in the population. (2) This results in separate gene pools . (3) Variation due to random mutatio...

The membrane of an axon contains a large number of protein channels along its length, which all fall under three categories: the sodium/potassium pumps, the voltage-gated sodium channels & the voltage-ga...

The Theory of Evolution states that organisms change (evolve) over a long time (from simple life forms) due to natural selection. Natural Selection: this is based on 3 key points. 1: that there is a lot of d...