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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...
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...
Blood from the body enters the right atrium of the heart via the vena cava. It then travels into the right ventricle by a combination of gravity and cont...
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