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There are a number of reasons why it is necessary to open and close the air vents. These include; allowing oxygen in, which is also necessary for respiration and allowing heat to escape. Closing the ai...

For the exams, the definition you will need to know is that "diffusion is the net movement of a substance from an area of high concentration to an area of low concentration, down a diffusion gradi...

The glucose level is regulated in pancreas by negative feedback loop, which means that when there is too much glucose, it is removed from the blood, and when there's too little, it is released into the...

To alter the size of the pupil, so the correct intensity of light is allowed through. Enough light is let through to allow clear vision, but not so much light that the retina might become damaged.

An enzyme is a globular protein that acts as a biological catalyst.  They work by reducing the activation energy of chemical reactions, which increases the rate of reactions.

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