Category: P

The optimum length or period of illumination required for the growth and maturation of a plant. The photoperiod is distinct from photosynthesis. The daily duration of exposure to light of a living thing.  

A single unit of light energy. The smallest quantity of electro magnetic energy; a particle with no mass and no charge; may occur in the form of x-rays, gamma rays, or quanta of light. An individual packet or particle of electromagnetic radiation. A light quantum or unit of energy of a light ray or other…

The actual free-energy change of ATP hydrolysis under a given set of conditions.  

Another name for the herbicide active ingredient glufosinate.  

The decrease in free energy as one mole of a phosphorylated compound at 1 .0 M concentration undergoes hydrolysis to equilibrium at pH 7.0 and 25°C (77°F). The energy that is available to do biochemical work. The energy arises from the breakage (cleavage) of a phosphate to phosphate bond.  

The first in a series of human tests of new pharmaceuticals mandated by the Food and Drug Administration (FDA). The primary purpose of the Phase I clinical test is to detect if the new pharmaceutical is toxic or otherwise harmful to normal, healthy humans. The conclusion of Phase I testing leads to Phase II and…

The portion of a molecule (e.g., a pharmaceutical) that is responsible for its biological activity (i.e., therapeutic action on recipient’s tissue, etc.). The three-dimensional shape of a molecule that makes it fit and activate cellular receptors.  

Another name for virus. A virus that attacks bacteria is known as a bacteriophage. Bacteriophages are frequently used as vectors for carrying (foreign) DNA into cells by genetic engineers.  

A single-celled microscopic algae which has a predator/prey relationship with fish in its ecosystem. During a large portion of its life cycle, Pfiesteria piscicida exists in a nontoxic cyst form at the bottom of a river. When those (cysts) detect certain substances (e.g., excreta) emitted by live fish, the Pfiesteria piscicida transform into an amoeboid…

The tendency of a compound (e.g., an insecticide) to resist degradation by biological means (e.g.. metabolism by microorganisms) after that compound has been introduced into the environment (e.g., sprayed onto a field) or by physical means (e.g., degradation caused by exposure to sunlight, moisture, etc.). The duration that a virus persists in a vector following…