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An efficient exchange surface should have a high surface area as this increases the rate at which diffusion can occur across it. For instance, roots have many root hair cells. These root hair cells have t...
Synapses are a gap or a junction between two neurones. When a nerve impulse is travelling along the axon of the first neurone and the impulse reaches the axon terminal (the end of the axon), a chemical ca...
Diffusion is the movement of particles (gases and liquids) from an area of high concentration to an area of low concentration. No energy is required (it is a passive process).Osmosis is the movement of wa...
The heart muscle is myogenic, meaning that it is able to initiate its own contraction. The wall of the right atria has a region of specialised fibres known as the sinoatrial node ...
A pathogen is a harmful organism that causes infectious diseases. There are many types of pathogens: bacteria, fungi, viruses, protoctists, worms and insects. They allow diseases to be transmitted from pe...
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