Biodiversity describes the variety of living things at multiple organizational levels: genetic, species and ecosystem diversity. Species diversity includes all branches of the evolutionary tree from single-celled prokaryotic organisms, bacteria, and archaea, to the eukaryotic kingdoms: plants; animals; fungi; and protists. To date, there have been about 1.75 million species identified, and new species are discovered every week.

Conservation biology is a scientific field that focuses on the preservation of biodiversity in order to protect ecosystems while meeting the needs of the human population. Humans require properly functioning ecosystems to maintain our supply of natural resources, including food, medicines, and building materials.

The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...

Nursing organizations play a vital role in representing nurses working in specialized clinical settings, such as the American Association of Critical-Care Nurses (AACN).
The AACN emphasizes a healthy work environment through six standards to achieve an optimal patient outcome. The standards are appropriate staffing, meaningful recognition, collaboration, authentic leadership, effective communication, and decision-making. In addition, AACN provides certification programs, webinars, journals, and...

Optical microscopy uses optic principles to provide detailed images of samples. Antonie van Leeuwenhoek designed the first compound optical microscope in the 17th century to visualize blood cells, bacteria, and yeast cells. In 1830, Joseph Jackson Lister created an essentially modern light microscope. The 20th century saw the development of microscopes with enhanced magnification and resolution.
In optical microscopy, the specimen to be viewed is placed on a glass slide and clipped on the stage...

Classification is the process of organizing organisms into hierarchically inclusive groups based on their phenotypic similarities or evolutionary relationships. A species comprises one or more strains, and closely related species are grouped into genera. Genera are further classified into families, families into orders, orders into classes, and so forth, up to the domain level, which is the broadest taxonomic rank derived from a combination of phenotypic and genotypic data.The nomenclature of...