Word Roots

aux- = grow, enlarge (auxins: a class of plant hormones, including indoleacetic acid, having a variety of effects, such as phototropic response through the stimulation of cell elongation, stimulation of secondary growth, and the development of leaf traces and fruit)

circ- = a circle (circadian rhythm: a physiological cycle of about 24 hours, present in all eukaryotic organisms, that persists even in the absence of external cues)

crypto- = hidden; -chromo = color (cryptochrome: the name given to the unidentified blue-light photoreceptor)

cyto- = cell; -kine = moving (cytokinins: a class of related plant hormones that retard aging and act in concert with auxins to stimulate cell division, influence the pathway of differentiation, and control apical dominance)

gibb- = humped (gibberellins: a class of related plant hormones that stimulate growth in the stem and leaves, trigger the germination of seeds and breaking of bud dormancy, and stimulate fruit development with auxin)

hyper- = excessive (hypersensitive response: a vigorous, localized defense response to a pathogen that is avirulent based on an R-Avr match)

photo- = light; -trop = turn, change (phototropism: growth of a plant shoot toward or away from light)

phyto- = a plant; -alexi to ward off (phytoalexin: an antibiotic, produced by plants, that destroys microorganisms or inhibits their growth)

stato- = standing, placed; -lith a stone (statolith: specialized plastids that help a plant tell up from down)

thigmo- = a touch; morpho- = form; -genesis = origin (thigmomorphogenesis: a response in plants to chronic mechanical stimulation, resulting from increased ethylene production; an example is thickening stems in response to strong winds)

zea- = a grain; -xantho = yellow (zeaxanthin: a blue- light photoreceptor involved in stomatal opening)

©2005 Pearson Education, Inc., publishing as Benjamin Cummings