496694
Descrição
Mapa Mental por kirareynolds, atualizado more than 1 year ago
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Criado por kirareynolds
quase 11 anos atrás
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How Plants Respond to the Environment
- Plant Growth
- The cell wall around a
plant cell limits the cell's
ability to divide and
expand.
- Growth only happens in
particular places in the
plant where there are
groups of cells cable of
dividing (meristems)
- Apical Meristems -
located at the tips or
apices of roots and
shoots and are
responsible for them
getting longer
- Lateral Bud
Meristems - found in
the buds. These
could give rise to
side shoots
- Lateral Meristems -
are found in a cylinder
near the outside of
roots and shoots and
are responsible for
them getting wider.
- The cell wall around a
plant cell limits the cell's
ability to divide and
expand.
- What causes phototropisms?
- In a phototropic response, a
shoot bends towards a light
source
- This happens because the
shaded side elongates
faster than the illuminated
side which pushes the end
of the shoot towards the
light
- This happens because the
shaded side elongates
faster than the illuminated
side which pushes the end
of the shoot towards the
light
- How the light causes redistribution
of auxin is still uncertain.
- Two enzymes have been
identified as phototropin 1
and phototropin 2.
- Their activity is promoted
by blue light hence there
is a lot of phototropin 1
activity on the light side.
- The gradient is thought to cause the
redistribution of auxins
- The gradient is thought to cause the
redistribution of auxins
- Their activity is promoted
by blue light hence there
is a lot of phototropin 1
activity on the light side.
- In a phototropic response, a
shoot bends towards a light
source
- Shedding Leaves
- Cytokinins stop the leaves of
deciduous trees senescing by
making sure the leaf acts as a
sink for phloem transport.
- This means the leaf is
guaranteed a good supply
of nutrients.
- This means the leaf is
guaranteed a good supply
of nutrients.
- If cytokinin productions drops
senescence begins
- Causes auxin production
at the top of the leaf to drop
- Makes cells in the abscission zone
more sensitive to ethene.
- Causes an increase in ethene production
- Increases production of the enzyme cellulose
which digests the walls of the cells in the
abscission zone, eventually separating the
petiole from the stem
- Increases production of the enzyme cellulose
which digests the walls of the cells in the
abscission zone, eventually separating the
petiole from the stem
- Makes cells in the abscission zone
more sensitive to ethene.
- Causes auxin production
at the top of the leaf to drop
- Cytokinins stop the leaves of
deciduous trees senescing by
making sure the leaf acts as a
sink for phloem transport.
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