Category: Biology Dictionary A

Definition Acetic acid is a mildly corrosive monocarboxylic acid. Otherwise known as ethanoic acid, methanecarboxylic acid, hydrogen acetate or ethylic acid, this organic compound is used in chemical manufacturing, as a food additive, and in petroleum production. The molecular formula of acetic acid is C2H4O2 or CH3COOH, where –COOH defines the presence of the single carboxyl…

Definition Abiotic factors, also called abiotic components are non-living factors that impact an ecosystem. Abiotic factors are part of the ecosystem and can impact the associated living things, but they are not living. The term “abiotic” comes from the root parts “a-” meaning “without,” and “bio,” meaning “life.” The living parts of an ecosystem are…

Abiogenesis Definition Abiogenesis is the creation of organic molecules by forces other than living organisms. While organisms can create carbon-carbon bonds relatively easily thanks to enzymes, to do so otherwise requires large inputs of energy. Early in the history of science, this fact was used to dispute evolution, as it could not be conceived how…

Abdominal Cavity Definition The abdominal cavity is a large cavity found in the torso of mammals between the thoracic cavity, which it is separated from by the thoracic diaphragm, and the pelvic cavity. A protective layer that is called the peritoneum, which plays a role in immunity, supporting organs, and fat storage, lines the abdominal cavity. As…

Abdomen Definition The abdomen refers to the region between the pelvis (pelvic brim) and the thorax (thoracic diaphragm) in vertebrates, including humans. The space constituting the abdomen is termed the abdominal cavity. The borders of the abdominal cavity are comprised of the posterior peritoneal surface, the anterior abdominal wall, the inferior pelvic inlet, and the…