Plant Adaptation: Reaction to
StimuliDaisy Mae A. Valeroso
Plant Cell
Plants grow slowly !
PLANT RESPONSES
Stimulus – Response
Process
Stimulus- change in
the environment
that causes a plant
to react
Response- plant’s
reaction to a
stimulus
Makahiya Plant
Tropisms- Responses of
plants to stimuli
- Could be negative
or positive
Positive Tropism – when a plant moves toward
the stimulus
Negative Tropism – when a plant moves away
from the stimulus
Phototropism Geotropism
Hydrotropism
Plant Tropisms
(Responses to stimuli)
Geotropism
(gravity)roots
Phototropism
(light)
Hydrotropism
(water)
Hydrotropism
(water)
Phototropism
(light)
Geotropism
(gravity)
Stems and leaves
Stems and leaves
roots
Stems and leaves
roots
Positive
Negative
Phototropism
NegativePositive
Geotropism
Positive Negative
Hydrotropism
Positive Negative
Situation
There are grasses growing in a
horizontally cut truck tire. They have
positive phototropism and negative
geotropism on its leaves and negative
phototropism and positive geotropism
on its roots.
Directions: Write TRUE if the underlined word is correct and if
it is false, write the correct word to make the sentence correct.
______ 1. Roots move toward the source of water but away
from the direction of light. Roots have positive
geotropism and negative phototropism.
______ 2. The leaves of a plant placed near a window would
eventually face the direction of light. Leaves have
positive phototropism.
______ 3. The roots need water to survive, therefore, roots
have positive hydrotropism.
______ 4. See weeds have positive hydrotropism.
______ 5. The roots of the orchids move downward but
away from the sunlight. Its flowers always face
toward the sun. Therefore, its roots have negative
geotropism, negative phototropism and its
flowers have positive phototropism.
Assignment
Observe a hanging plant.
Identify its positive and negative
tropisms and explain the reason in 2
to 4 sentences. Write it on a sheet of
paper.
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