Subject: why are plants stiff and immobile due to their cellular structure?

plants are stiff and immobile. how does their cellular structure contribute to 
this characteristic?

is it because of their cell wall? im really not sure. my father is an english 
teacher, so he cant ever answers my question. ironic eh? he always tells me to 
check out www.madsci.org, and ask people like you. so hear i am. :)please help 
me, because these weekly trivia questions asked by my uncle drive me CRAZY!!! 

Re: why are plants stiff and immobile due to their cellular structure?