Tropisms and Homeostasis

A tropism is...

• a change in the environment

• plant growth in response to a stimulus

• something that causes a response

• when photosynthesis takes place

What is the stimulus in this example?

• Internal

• Light

• Touch

• Temperature

Tags

NGSS.4-LS1-2

NGSS.4-PS4-2

Roots of a tree growing towards the water line of a house.

• Geotropism

• Phototropism

• Thigmotropism

• Hydrotropism

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-4

The shoot of a plant growing up.

• Positive geotropism

• Negative geotropism

• Thigmotropism

• Hydrotropism

Tags

NGSS.MS-LS1-5

The root of a plant growing down.

• Positive geotropism

• Negative geotropism

• Thigmotropism

• Hydrotropism

A plant growing in response to a greenhouse light.

• Geotropism

• Phototropism

• Thigmotropism

• Hydrotropism

Tags

NGSS.MS-LS1-6

Venus Flytrap flower reacts to a bug.

• Thermotropism

• Negative Geotropism

• Thigmotropism

• Hydrotropism

Tags

NGSS.MS-LS2-1

Rhododendron leaves close in cold weather.

• Heliotropism

• Thigmotropism

• Phototropism

• Thermotropism

What makes a tropism positive or negative?

• Positive = movement towards stimulus, Negative = movement away from stimulus

• Negative = movement towards stimulus, Positive = movement away from stimulus

• Who cares? It doesn't matter whether it is positive or negative

• Positive = when a plant is happy, Negative = when a plant is sad

Plant growth factors are produced:

• In tissues located all around the plant

• In tissues near their effect

• In the tissues which they will affect

• In particular organs of the plant