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Pupils can either dilate or constrict in response to changes in light intensity.

In very bright light - the eyes constrict - as a protective mechanism
In very dull light/dark conditions - ...

In a population, random mutations of alleles will produce variation. Some of these mutations might be really helpful for the organism that has them and helps them to survive in their environment better. T...

The fluid mosaic model is a model used to describe the cell membrane and the transport of molecules through it. It is a semi permeable membrane which means that it is selective in the molecules that it al...

Active transport is the transport of substances against their concentration gradient with the use of energy. Molecules naturally flow down their concentration gradient, ie. from where they are more concen...

The process of cell division in human tissue cells is called mitosis. Before the cell begins to divide, it grows and duplicates all the sub-cellular structures like ribosomes and mitochondria. Inside the ...