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Standard Deviation

Standard deviation measures how spread out data is and is a measure of the amount of variation in a data set.The greater the standard deviation, the greater the spread of the data and the greater the amount of variation.Standard deviation is given by:
68% of all values fall within ±1 standard deviation from the mean.95% of all values fall within ±2 standard deviations from the mean.99.7% of all values fall within ±3 standard deviations from the mean.

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Specification: OCR Biology A (H020), AS-level, 4.2.2 Classification and evolution. Topic: Classification and Evolution.

Key terms in this lesson

disulfide bridge
A covalent bond formed between two cysteine residues that helps stabilise the tertiary or quaternary structure of a protein.
tertiary structure
The overall three-dimensional shape of a single polypeptide chain, formed and held by bonds between R groups.
glycoprotein
A protein with a carbohydrate chain attached, often found on the cell surface acting as a receptor or antigen.
pathogen
A microorganism that causes disease.
antigen
A molecule, usually a protein, on the surface of a cell or pathogen that triggers an immune response.

More in Classification and Evolution

All 36 lessons in Classification and Evolution · All OCR AS-level Biology topics