Unit 11: Plants Response to the Environment
Unit 11: PlantsResponse to the Environment
Response to the EnvironmentThey know what's happening...
Tropism:The growth or movement of a plant in RESPONSE to a STIMULUS.
Plant responding to touch stimulus
Person responding to heat stimulus
Lack of response to a stimulus
a.k.a Tropic Responses
1. Phototropism2. Gravitropism3. Thigmotropism
1. Phototropism
Photo = LIGHT
Tape the correct picture in the box.
Phototropism is a plant’s response to light. It will grow TOWARDS any light source that it senses. Because you know, photosynthesis. (They need lots of light)
2. GravitropismTape the correct picture in the box.
Gravitropism is a plant’s response to gravity. No matter what way you turn a plant, it will grow stem up and roots down. They can tell up from down.
Gravi = GRAVITY
Root growing down
Root growing down
Root growing down
Plant growing up
Plant growing up
Plant growing up Plant growing up
Seed = right side up
Seed = upside down Seed = sideways
3. ThigmotropismTape the correct picture in the box.
Thigmotropism is a plant’s response to touch. Some plants (like vines) feel to wrap themselves around something. Other plants like venus fly traps, sense touch and close up.
Thigmo = touch
Hormones: Not Just For PeopleHormones are like chemical text messages. They signal cells to start or stop doing certain things. In plants, hormones control things like rate of cell growth, shape of cells, and fruit ripening.
How hormones work - just read this partWhen certain situations arise, hormones increase or decrease based on the need. Then they cause the plant to respond in a certain way.
It would be like if you really like a person, so you increase the amount of texts you send them. If they like you back, they will probably respond to you. Then you will be happy.
If they don’t like you back, they will probably not respond to you. Then you will be sad.
Situation ----> Hormone Level ----> ResponseNot enough water
is reaching the roots because they
are too short
Plant makes more AUXIN
(AUXIN levels increase)
AUXIN tells roots cells to divide more, causing them to grow longer
Situation ----> Hormone Level ----> Response
Plant is too short to get sunlight
Plant makes more GIBBERELLIN(GIBBERELLIN
levels increase)
GIBBERELLIN causes the stem cells to divide more,
making the plant grow taller
gibberellin gibberellingibberellin
gibberellin gibberellingibberellingibberellin
gibberellingibberellingibberellingibberellingibberellin
Situation ----> Hormone Level ----> Response
Bananas picked before they were ripe. Too green to
make banana bread
Put them in a paper bag to collect the
ETHYLENE (ETHYLENE levels
increase)
ETHYLENE gets absorbed into the banana peel cells, causing them to
ripen faster. Now you can make banana bread!
ETHYLENE
ETHYLENEETHYLENE
ETHYLENEETHYLENE
ETHYLENE
ETHYLENE
Situation ----> Hormone Level ----> ResponsePlant is growing too
fast. There aren’t enough nutrients
available to support growth, plant is thin
and skinny
Plant makes less CYTOKININ
(CYTOKININ levels decrease)
Less CYTOKININ causes cells to divide more
slowly, causing plant growth to slow down
cytokinin
cytokinin
Hormone Overview - Just FYI
Hormones Other StuffHormones are what control a plant's response to the environment. Plants respond to their needs (similar to you) like water, sunlight, and support.
At the bottom of your notesIf you had to guess what HYDROTROPISM was a response to what would you guess based on the word?
Write your answer at the bottom of your notes.
Picture is unrelated to
the question.