Download Warm-up: Where would you expect to find stomata on pond lillies?

Warm-up: Where would
you expect to find stomata
on pond lillies?
How can aphids help us
understand phloem function?
Nutritional Symbiosis
!   Bacterium that lives INSIDE aphid gut cells. (Intra-cellular
BACTERIOCYTE).
!   Aphid cannot make 10 essential amino acids.
!   Phloem sap contains almost NO protein.
! Bacteriocyte makes amino acids for the aphid.
Ultrastructure of a Bacteriocyte
Nucleus in
the center.
Buchnera
cells packed
around it.
Homeostasis in humans
Use chemical (hormones) and
electrical (nerves) mechanisms to
regulate responses to
environmental change.
How do plants maintain homeostasis?
Plant responses are
primarily mediated by
hormones
Hormones
Chemical messengers
Produced in one part of an organism
and released to have an effect on
another part of the organism.
Plant responses: tropisms
!   Light: phototropism
!   Day-length: flowering, seed germination
!   Gravity: shoots grow up, roots grow down
!   Temperature: growth
Tropism = growth response
to a stimulus
Plants: exhibit indeterminate growth
in regions called “meristems”
Animals: determinate growth
!P
  eriods of rapid cell division
and growth (embryonic,
juvenile periods).
!A
  fter this, growth slows or
stops
Plant hormone: Auxin
Primary auxin is IAA
(indole-3-acetic acid)
Plant hormones affect growth:
apical dominance
Tropism: Plant response to stimuli
which is growth mediated
Auxin effects