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Stems

Stems primarily provide plants structural support. This tutorial includes lectures on the external form of a woody twig ..

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Birth Control and Contraception

Different pregnancy and birth control and contraception strategies are described. Read this tutorial to learn each of th..

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Human Biology – Food and Digestion

This tutorial recognizes the importance of food as a source of energy that will fuel many biological processes. A good d..

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Dominance

This tutorial presents Gregor Mendel's law of dominance. Learn more about this form of inheritance and how it can be pre..

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Plant Cell Defense

Plants protect themselves by releasing hydrogen peroxide to fight against fungal invasion. Another way is by secreting c..

Disturbance on a still water
Abiotic Factors – Water Conditions

A still body of water may be disturbed by a variety of factors. One of them is wind. In fact, it is considered as the pr..