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Natural Selection, Species Isolation and Real World Example

By: HWC, Views: 6062

`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 ...

Mycobacterium tuberculosis: Drug Resistance and Natural Selection

By: HWC, Views: 5408

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...

Cellular defenses (natural killer cells, phagocyte types & process of phagocytosis)

By: HWC, Views: 6467

• Lymphocytes that rapidly defend against abnormal (cancer) or virus-infected cells. • Found in blood, spleen, lymph nodes, and red bone marrow. • Lack receptors for binding with specific antigens. • Act upon cells displaying abnormal MHC antigens. • NK cells destroy cells in ...

How does an animal choose what food to eat?

By: HWC, Views: 6112

One might assume that natural selection has influenced the foraging behaviors of animals, and that most animals forage efficiently, spending the least energy to gain the most nutrients. This is the underlying assumption of optimality modeling, a scientific approach to studying foraging behavior. ...

Cardiac conductile cells

By: HWC, Views: 6869

• In order for the heart to function properly, all of its cells must contract in a specific sequence. This sequence is determined by a pathway known as the conduction system. • Cardiac muscle cells have two attributes that enable the conduction system to work: • Connective. Action pot...

How antibiotics works? 💊

By: HWC, Views: 6315

The Crisis in Antibiotic Resistance More than 70 years ago, Alexander Fleming discovered penicillin. A few decades later, when this antibiotic was used in World War II, Fleming's discovery had revolutionized medicine. No longer did people have to die from something as trivial as an infected cut.Y...

Mendel's Principles of Inheritance (Father of Genetics)

By: HWC, Views: 6287

Gregory Johann Mendel, a monk living in the mid-1800's, is known as the "Father of Genetics" for his experiments with pea plants in the abbey garden. These experiments led him to deduce the fundamental law of genetics. Mendel was an Augustinian friar who entered, in 1843, the Abbey of St. Thom...

How Broken Bones Repair Themselves

By: Administrator, Views: 339

Bone healing, or fracture healing, is a proliferative physiological process in which the body facilitates the repair of a bone fracture. Generally bone fracture treatment consists of a doctor reducing (pushing) displaced bones back into place via relocation with or without anaesthetic, stabili...

Primary and secondary response to infection

By: HWC, Views: 6365

• Pathogens enter the body by penetrating the non-specific barriers in the skin and mucus membranes. • Pathogens first encounter macrophages and natural killer cells that carry out phagocytosis and cytolysis respectively. • A pathogen's first encounter with the immune system can promo...