Fermentation is a metabolic process that converts sugar to acids, gases, or alcohol. It occurs in yeast and bacteria, and also in oxygen-starved muscle cells, as in the case of lactic acid fermentation.
pupil noun [C] (EYE PART). âº the âcircular âblack âarea in the âcentre of an âeye, through which âlight âenters: Pupils âcontract in âbright âlight, and âdilate in darkness. (Definition of pupil from the Cambridge Advanced Learners Dictionary & Thesaurus Â© Cambridge University Press).
Etymology: L, pupa, doll. a circular opening in the iris of the eye, located slightly to the nasal side of the center of the iris. Like the iris, the pupil lies posterior to the cornea and the anterior chamber of the eye and is anterior to the lens. Its diameter changes with contraction and relaxation of the muscular fibers of the iris as the eye responds to changes in light, emotional states, and autonomic stimulation.