A Level Biology Revision Notes

Comprehensive A Level Biology revision notes providing information and assistance for all UK examination boards (AQA, OCR, Edexcel) as well as international curriculum (CIE).

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Natural Selection

The theory of natural selection by Charles Darwin is a vital milestone in the origin of species and the evolutionary process. Many scientists before Darwin stated that a species evolves from an ancestor or from a different species. However, no scientific evidence was present at that time to prove the idea of evolution. During 19th …

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pH and Buffers

The acidity of the solution The number of hydrogen ions present in a solution is a measure of the acidity of the solution. All acids do not ionize completely when dissolved in water, i.e., all the molecules of acid do not ionize and exist in the solution as electrically-charged particles. The hydrogen ion concentration is …

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Glycolysis Steps, Pathway & Cycle


Glycolysis is the first step in the breakdown of glucose to extract energy for cellular metabolism. Glycolysis consists of an energy-requiring phase followed by an energy-releasing phase. Glycolysis is the sequence of 10 enzyme catalyzed reactions that converts glucose into pyruvate with the simultaneous production of ATP. The overall reaction of glycolysis which occurs in …

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