1. Photoperiodism- physiological response to day/night length
ex: flowering
short-day plants - requires shorter period of time exposed to light to flower
ex: poinsettias, chrysanthemums (late summer, fall, winter)
long-day plants - requires longer exposure to light to flower
ex: spinach, radish, lettuce (late spring, early summer)
day-neutral plants - unaffected by photoperiod
ex: dandelions, tomatoes, rice (flower at certain maturity point
regardless of time of year)

2. *control systems allow plants to cope with environmental stressors
ex: stomata closing - conserve water in drought
roots with air tubes to get O2 if water logged
production of compatible salts to respond to salt increase
heat-shock proteins to protect other proteins during heat stress
lipid composition adjustment in cold
physical & chemical defense to fight herbivory
salicylic acid - used against pathogens

3. Signal transduction pathways:
-hormones stimulate cells by binding to specific receptors (reception)
-reception triggers second messengers to be produced within cell (transduction)
-2nd messengers activate a chain of events that mobilize the cell’s specific response (induction)