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Birth Control and Contraception
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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The Dinosaurs

Dinosaurs represented a major turn in the evolutionary development of organisms on Earth. The first dinosaurs were presu..

human brain structure
The Conscious & Unconscious Nervous System

This tutorial elaborates on how the nervous system works, particularly at the tissue level of the brain. There are three..

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Sleep and Dreams – Neurology

While learning and intelligence are associated with the functions of a conscious mind, sleep and dreams are activities o..

An artist depiction of a Precambrian multicellular life form.
The Evolution of Cell Organelles

The nucleus containing the genetic material, DNA, and the mitochondria, well-identified as the "powerhouse of the cell",..

An artistic depiction of Dunkleosteus fish
Fish

The sea was teeming with life. Eventually, through reproduction and continued variation, fish came about. There are over..