Category: Biology Dictionary B

Biogeochemical Cycle Definition A biogeochemical cycle is one of several natural cycles, in which conserved matter moves through the biotic and abiotic parts of an ecosystem. In biology, conserved matter refers to the finite amount of matter, in the form of atoms, that is present within the Earth. Since, according to the Law of Conservation of Mass, matter cannot be created or…

Biofilm Definition A biofilm is a thick layer of prokaryotic organisms that have aggregated to form a colony. The colony attaches to a surface with a slime layer which aids in protecting the microorganisms. There are a number of reasons why biofilms are formed, all of which promote growth and survival or the microorganisms. Biofilms…

Why is Biodiversity Important? Without biodiversity, the health of the planet is at stake. Every single species has a role to play, although some – like viruses and disease-carrying mosquitoes – are considered to be damaging to the well-being of humans and other organisms and steps are being taken to eradicate them. A healthy ecosystem…

Biochemistry Definition Biochemistry is the study of the chemical reactions that take place inside organisms. It combines elements from both biology and chemistry. Biochemistry became a separate discipline in the early 20th Century. Biochemists study relatively large molecules like proteins, lipids, and carbohydrates, which are important in metabolism and other cellular activities; they also study molecules…

Bioavailability Definition When a substance such as a medicine or supplement enters your system, the portion of the total substance introduces which can effectively create a response determines that substance’s bioavailability. The bioavailability of a substance can fluctuate, depending on the route of administration. Intravenous administration, or a direct line into the bloodstream, is typically considered 100% bioavailability,…

Binomial Nomenclature Definition Binomial nomenclature is the system of scientifically naming organisms developed by Carl Linnaeus. Linnaeus published a large work, Systema Naturae (The System of Nature), in which Linnaeus attempted to identify every known plant and animal. This work was published in various sections between 1735 and 1758, and established the conventions of binomial nomenclature,…

Binary Fission Definition Binary fission is the process through which asexual reproduction happens in bacteria. During binary fission, a single organism becomes two independent organisms. Binary fission also describes the duplication of organelles in eukaryotes. Mitochondria and other organelles must reproduce via binary fission before mitosis so each cell has ample organelles. Binary Fission Overview…

Bilirubin Definition Bilirubin is a molecule formed from the breakdown of red blood cells, and other cells with porphyrins. Red blood cells carry special molecules, called hemes (a type of porphyrin), which hosts an iron atom. This arrangement allows the red blood cell to carry oxygen. When blood cells break down, they release the heme into the blood,…

Definition Bile salts are found in bile, a secretion produced by liver cells to aid digestion. Although bile is 95% water, bile salts are its most prominent organic solutes and play a major role in fat emulsification. Human bile contains at least twelve bile salts. Only two of these are primary or synthesized in the…

Bilateral Symmetry Definition Bilateral symmetry refers to organisms with body shapes that are mirror images along a midline called the sagittal plane. The internal organs, however, are not necessarily distributed symmetrically. The vast majority of animals display bilateral symmetry; also known as plane symmetry, this is a trait that applies to 99% of all animals, in the…