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Primate Evolutionary Tree Animation

By: HWC, Views: 2813

Presumed evolutionary branchings in the primate family tree. The first primates arose between 85 and 65 million years ago. The common ancestor of apes and hominids branched off from Old World monkeys about 23 million years ago. The hominid lineage, which includes humans and earlier humanlik...

Griffith's experiments

By: HWC, Views: 3797

In the late 1920s, Fred Griffith was attempting to develop a vaccine against a bacterium that causes pneumonia. To find out why two strains of the bacteria differed in their deadliness, he injected mice with four different mixtures. Mice injected with R cells remained healthy. When Griffith ex...

Smoking Cessation

By: Administrator, Views: 9531

Smoking cessation (also known as quitting smoking or simply quitting) is the process of discontinuing tobacco smoking. Tobacco smoke contains nicotine, which is addictive and can cause dependence. Nicotine withdrawal makes the process of quitting often difficult. Seventy percent of smokers wou...

Role of the respiratory system - effect of altered ventilation rates

By: HWC, Views: 6548

• Dissociation of the chemical substances in the body fluids can result in the production of free hydrogen ions. • The pH scale is used to measure the concentration of hydrogen ions in solution. • Normal blood pH values vary around 7.4. • When hydrogen ion concentration increases, t...

Cataract

By: Administrator, Views: 9497

A cataract is a clouding of the lens in the eye which leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble with bright lights, and trouble seeing at night. This may re...

Introduction to Epilepsy

By: Administrator, Views: 9781

Epilepsy is a group of neurological disorders characterized by epileptic seizures. Epileptic seizures are episodes that can vary from brief and nearly undetectable periods to long periods of vigorous shaking. These episodes can result in physical injuries, including occasionally broken bones. In ...

Predator- prey competition and symbiosis

By: HWC, Views: 6492

Predator-prey relationships occur when one species, the predator, kills and eats an organism of another species, the prey. This graph shows the cyclical nature of predator-prey relationships, in this case among populations of Canada lynx and snowshoe rabbits. If predation is without some li...

Magnetic resonance imaging (MRI)

By: Administrator, Views: 9779

Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body in both health and disease. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the or...

Structure of Amino Acid, Peptide Bonds & Polypeptides

By: HWC, Views: 6154

Here are the molecular formulas of three different amino acids. All amino acids share this backbone. The main difference between every amino acid is the side groups seen here, and these side groups give each of the amino acids their different characteristics. But before we get into that, let's ...