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).
But this hole has a lot to do with how you see. The pupil of the eye is the black circle in the center of your iris. The iris is the colored ring in your eye whose color and structure is as individual as you are. From the outside of the eye, light passes through the clear lens, then through the hole that is the pupil.