Search Results

How to find out if a population is evolving?

By: HWC, Views: 4704

Imagine a butterfly population with a pair of alleles that influence wing color as shown. We will represent the frequency of the dominant allele as p and the recessive allele as q. The Hardy-Weinberg rule describes what happens if a population is at genetic equilibrium—if it is not evolving...

Mycobacterium tuberculosis: Drug Resistance and Natural Selection

By: HWC, Views: 6481

The evolution of drug resistance in microorganisms, such as M. tuberculosis, that cause human diseases is of particular concern to biologists. When Mycobacterium tuberculosis infects the lungs of humans, it causes the disease tuberculosis, also called TB. Once infected, the lungs act as a new...

Natural Selection, Species Isolation and Real World Example

By: HWC, Views: 7151

`Natural selection' is the process in which organisms with adaptive traits survive and breed in greater number than organisms without such traits. Eventually, almost all of the individuals in the population will have the same adaptive trait. This was the concept presented by Charles Darwin in ...

Olfaction. or the sense of smell

By: HWC, Views: 5140

Do you ever wonder how you can distinguish thousands of different odors? Olfaction. or the sense of smell, is used by all mammals to navigate, find food, and even find mates. We have millions of olfactory receptors for smelling in our nose. These receptor neurons bind water-soluble or volatil...

Introduction to Genetics

By: Administrator, Views: 10629

Genetics is a branch of biology concerned with the study of genes, genetic variation, and heredity in organisms. Gregor Mendel, a scientist and Augustinian friar, discovered genetics in the late 19th-century. Mendel studied "trait inheritance", patterns in the way traits are handed down from p...

Studying the Left and Right Brain Independently

By: Administrator, Views: 10974

A seizure, technically known as an epileptic seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with loss of consciousness (tonic-clonic seizure), to shakin...

Diversity of Living Creatures - Charles Darwin & the Beagle's Voyage

By: HWC, Views: 7460

As we look around at the living creatures on Earth, we see a great amount of diversity. In some cases, the differences are quite noticeable, like the differences between plants and animals. Some differences are not as easy to see, like the differences between two species of lizard. How did all...

Predator- prey competition and symbiosis

By: HWC, Views: 7526

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...

Griffith's experiments

By: HWC, Views: 4860

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...