Behavior = the manner in which a personbehaves in reacting to social stimuli or toan inner need or to a combination thereof;

OR = good manners

OR = an activity of a defined organism, especially observable activity when measurable in terms of quantifiable effects on the environment whether arising from internal or external stimuli

OR = anything that an organism does that involves action and response to stimulation

OR = the response of an individual, group, or species to the whole range of factors constituting its environment

Plant Life Cycle: includes stages of dormancyprocesses of mitosis, cell expansion, differentiation, fertilization (twice!)

Plant Development is flexbile:indeterminate, cells toti-potent

Corn (Zea mays)

produces male flowers(tassel)

and female flowers(many make up the ear)

the plants can ‘self’ oroutcross

a pollen grain germinatingon a style must extend itstube down the length ofthe style (12 inches or so)and fertilize the embryoat the end of the stylein order to make a kernel(ovule) develop

Once and embryo is formed, it can undergomitosis (cell division), and differentiation tomake all the different cell types, tissues andorgans of a plant. This process is calleddevelopment.

Development is regulated at three levels:

Genetic – by control of the pattern of geneexpression, cells determine whichproteins, structures and processesare active

Internal signaling – signals include ‘hormones’other metabolites (sugars, peptides)hydraulic and electric signals

External signalinglighttemperaturewaternutrientbiotic interactions

Plant ‘hormones’ or growthregulators are active at nM levels.

Their activity depends on:

1) rate of synthesis2) rate of transport to active site3) receptivity of target/presence

of receptor4) rate of degradation

Germination:

• dormancy must be broken• seed imbibes water• tissues rehydrate• embryo releases GA• aleuroce cells respond to GA• endosperm digested• embryo begins to grow• root elongation followed by shoot/leaves

Seeds are like tiny space ships, launched from their mother into space, packed fullof food, primed to germinate if or when they land on suitable substrate.

Some seeds require light as a cue for germination.The photoreceptor responsible for this sensory process is Phytochrome – red (660 nm)/far red (730 nm) photoreceptor ‘switch’

phytochrome is aprotein with enzymeactivity (kinase), bound to a chromophore;when the chromophoreabsorbs R or FR light,it changes the proteinconformation, thusactivating/inactivatingthe enzyme