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    Why do auxins and gibberellins seem to have similar roles? In my book it says 'auxins promote cell elongation, inhibit growth of side shoots; inhibit leaf abscission (leaf fall)' and 'gibberellins promote seed germination and growth of stems'. Isn't 'cell elongation' and 'growth of stems' the same thing? Shouldn't they have different roles?
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    Well, their modes of action are different. Auxins promote enzymes that loosen cell wall bonding, and as a consequence, water rushes in to elongate cell (with an associated H+ ions action). Gibberelins behave a bit like red light in photoperiodism, they promote germination and flowering in long day plants. They are also involved in vernalisation.
    Also groth would mean an increase in number of cells, while cell elongation is an altogether different phenomenon.
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    (Original post by Dynamo123)
    Well, their modes of action are different. Auxins promote enzymes that loosen cell wall bonding, and as a consequence, water rushes in to elongate cell (with an associated H+ ions action). Gibberelins behave a bit like red light in photoperiodism, they promote germination and flowering in long day plants. They are also involved in vernalisation.
    Also growth would mean an increase in number of cells, while cell elongation is an altogether different phenomenon.
    I see what you mean, but doesn't an increase in the number of cells only occur in meristems and not shoots?
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    Yeah, but apical meristems in shoot cause primary growth and division of cells in shoots too.
 
 
 
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