Benders'dictionary of nutrition and food technology

373photosynthesis Sequence of reactions, most commonly in plants,but also in some micro-organisms, that leads to synthesis of carbohydratesby reduction of carbon dioxide using light as theprimary energy source. Considered in two separate reactionsequences: the light phase, in which light energy is captured bycarotenoids, and transferred to chlorophyll, leading, via anelectron transport chain, to the reduction of NADP + to NADPHand the synthesis of ATP from ADP and phosphate; the darkphase in which NADPH and ATP are used to reduce carbondioxide to glucose.There are two separate pathways for the dark phase reaction:the C3 pathway (Calvin cycle), in which phosphoglyceric acid isthe first product of CO 2 fixation, and the C4 pathway (Hatch andSlack pathway), in which four-carbon dicarboxylic acids are thefirst products of CO 2 fixation. Both pathways may occur togetherin some plants; the C4 pathway is found especially in maize,sorghum, sugar cane and tropical grasses growing under highlight intensity where water is scarce.phrynoderma Blocked pores or ‘toad-skin’ (follicular hyperkeratosisof the skin) often encountered in malnourished people.Originally thought to be due to vitamin a deficiency but possiblydue to other deficiencies, and also occurs mildly in adequatelynourished people.phthisis Obsolete name for any disease resulting in wasting oftissues; see cachexia; protein–energy malnutrition.phulka See chappati.phycotoxins Marine biotoxins that accumulate in fish and shellfishfrom their diet (causing paralytic shellfish poisoning andciguatera poisoning when the fish are eaten), as distinct fromtoxins naturally present (tetramine poisoning).phyllo pastry (filo pastry) Plain paper-thin pastry made from flourand water, rolled into small balls then tossed in the air andstretched until it forms an extremely thin sheet. Multiple layersare used as the basis for Greek and Middle-Eastern pastrydishes. Known as mortoban in south-east Asia.phylloquinone See vitamin k.phylloxera An aphid which threatened to destroy the vineyardsof Europe in the middle of the 19th century. They were savedby grafting susceptible varieties onto resistant American vinerootstock.physalin A carotenoid, zeaxanthin dipalmitate, in the fruits ofthe cape gooseberry, Physalis spp.Physalis See cape gooseberry.physical activity level (PAL) Total energy cost of physical activitythroughout the day, expressed as a ratio of basal metabolic