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What is diffusion? (GSCE: OCR, Edexcel, AQA)

Definition : diffusion is the spreading out of particles from an area of high concentration to an area of low concentration The theory: Diffusion, is the scientific description for the gradual movement of pa...
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Answered by Ned F. • Biology tutor
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What are pathogens and how do they cause disease?

Pathogens are microorganisms that can cause disease. Pathogenic bacteria make us ill in 2 way: 1) by damaging body cells 2) releasing toxins. Pathogenic viruses invade body cells where they use the cellular ...
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Answered by Golnoush G. • Biology tutor
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What is a reflex arc and how does it work?

A reflex is an unconcious response to a potentially harmful stimulus, such as pulling a tray out of the oven without oven gloves on! Reflexes bypass the brain and instead have a circuit that only passes thro...
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Answered by Polly C. • Biology tutor
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Explain the process of allopatric speciation

A population of one species is separated by a physical barrier, e.g a geographical barrier such as the movement of tectonic plates. There will then be 2 isolated groups of the same species unable to interbre...
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Answered by Matthew S. • Biology tutor
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Name 3 features of a plant cell not found in an animal cell

Plant cells have chloroplasts, a vacuole and a cell wall.
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Answered by Matthew S. • Biology tutor
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