Transcript Tropisms

Tropisms
C-Scope
Unit 1
Lesson 2
How do plants grow?
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From seeds or other plant parts
They grow to continue species
Seeds come from flowers on plants, all plants
have flowers you just might not be able to see
them.
What do plants need to grow?
Water
 Sunlight
 Correct Temperature
 Space
 Food
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Parts of a seed
Seed Coat
 Cotyledon
 Root
 Stem
 Leaves
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How do seeds emerge?
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It responds to gravity, light, temperature, and
water.
When all conditions are right the seed will use
the cotyledon to push up from the soil towards
the sun and the roots are pulled down by
gravity.
Plants in Space
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As early as 1984 NASA has been
experimenting with plants in space.
The problem that NASA is trying to overcome
are the tropisms.
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Hydrotropism
Phototropism
Geotropism
Thigmotropism
Hydrotropism
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This is the plants reaction to water.
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The roots will grow towards the water
This is a problem in space because the space
shuttle cannot carry extra water to water the
plants (space and weight)
Since space is an issue, the astronauts have one
water source and all the plants grow roots
towards the water to save room.
Where do the water and nutrients
come from?
Phototropism
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NASA has done many experiments with light
and plants because Space can be a very dark
place.
Phototropism is a plant’s reaction to light,
plants will grow towards light.
Geotropism
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Geotropism is the plants reaction to gravity.
Usually roots grow down towards the center of
gravity and shoots grow towards the sun.
The is very little gravity in space, it is called
microgravity.
This presents a huge problem to plants since
there is little light and almost no gravity.
NASA Experiments
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When NASA started doing experiments in the
dark and in space many interesting things
started to happen to the plants.
The plants started to grow in circles.
Back On Earth
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Thigmotropism
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Plants response to touch
Plant will send out a feeler and when it touches
something it will start to wrap around it.
It is how a plant climbs up things