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The reflex arc is a pathway that contorls a reflex action. Reflex actions are very fast (milliseconds fast) which can help in dangerous situations. For example, if I touch a hot pan, the reflex would be m...

Mitosis is the division of diploid (full set of 46 chromosomes)  cells, to form two diploid daughter cells with an identical nature to their parent cells. This occurs throughout the body during cell repla...

There are five main features that effect the rate of diffusion:

The rate of diffusion INCREASES if there is a short diffusion path because there is less chance of collision of particles.

The...

Lungs contain millions of alveoli which act as the gas exchange surface for the body, O2 is absorbed and Co2 is excreted by the body via the lungs which contain a large number of small 'air sacs' known as...

Emphysema affects the structure of the lungs called the alveoli. Each healthy alveolus has a large surface area in order for maximum diffusion of oxygen in the lungs.

If someone is affected by emph...