Plants & External Stimuli

When someone shines a bright light in your face, how do you respond?

Essential Question

How do plants respond to external stimuli?

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Dormancy:• A period of time when growth or activity of a

plant or seed stops due to changes in temperature or amount of water

• This allows the plant to survive in certain environments

• Seeds will grow in conditions that are favorable (good) for survival.

• Ex. Leaves fall from tree in Fall and leaf buds come back in Spring; Apples fall to ground in Fall and don’t grow until Spring.

How do you think plants loosing their leaves helps them to survive?

Phototropism• A plant grows or moves in response to

light.

• Illustrate phototropism.

How would moving towards light help a plant survive?

Gravitropism:• A plant grows or moves in response to

gravity• Also called geotropism.

• Illustrate gravitropism.

How would growing with gravity help a plant survive?

Hydrotropism• A plant moves or grows in response to

water.

• Illustrate hydrotropism.

How would growing towards water help a plant survive?

Thigmotropism• A plant moves or grows in response to

touch.

• Illustrate thigmotropism.

How would growing towards something it touches help a plant survive?

Tropisms

How do plants grow in space? Setting up the experiment

How do plants grow in space? Experiment Results

What’s the tropism?

What’s the tropism?

What’s the tropism?

What’s the tropism?