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).
The pupil is an opening that lets light into your eye. Since most of the light entering your eye does not escape, your pupil appears black. In dim light, your pupil expands to allow more light to enter your eye. In bright light, it contracts.ou can also experiment to determine how light shining in one eye affects the size of the pupil in your other eye. 1  A magnifying glass (at least 1 inch [2.5 cm] in diameter). 2  A mirror (a small, flat, compact mirror, a plastic mirror 4 x 4 inches [10 x 10 cm] or larger, or a wall mirror). 3  A flashlight.