Plants Move

TROPISMis a biological phenomenon,

indicating growth or movement of a plant in response

to an environmental

stimulus

TROPISMPOSITIVE

If the plant moves TOWARD the stimulus

NEGATIVEIf the plant moves AWAY from the stimulus

Phototropism

Movement of plants toward light

Why? To maximize amount of sun for photosynthesis to make their food.

Gravitropism

http://www.youtube.com/watch?v=mYZXax8V_L0&feature=related&safety_mode=true&persist_safety_mode=1

Movement of plants in response to gravityPositive is toward gravity (roots grow down)Negative is away from gravity (shoot, stems, and leaves grow up)Why? Allows plants to grow properly and get nutrients and sunlight

Hydrotropism

http://virtualastronaut.tietronix.com/textonly/act25/text-plants.html

Movement by plants toward water.Why? Roots search for and grow toward water, because it is needed for photosynthesis and to support cell structure.

Thigmotropism

http://www.youtube.com/watch?v=8HeedWWe6VA&feature=related&safety_mode=true&persist_safety_mode=1

Plants moving in response to touch.Positive is toward touch (vines wrap around structures)Negative is away from touch (some plants close up when touched)

Why? to support leaves as they grow higher to reach the sun to make more food (photosynthesis).

GravitropismGravity causes a response in plant

growth

In the picture above, which part of the plant exhibits positive tropism, and which exhibits negative tropism?

HydrotropismThe way a plant grows or bends in

response to water

Why would it be important for some parts of a plant to be pulled toward water?

ThigmotropismPlants bend and grow because of touch.

What are some other ways a plant can be “touched”?

PhototropismThe way a plant grows or bends in

response to light.

Why do you think sunflowers were given their nickname?

Hydroptropism

Phototropism

Gravitropism

Phototropism

Thigmotropism

TROPISM QUIZ

Identify the type of tropism in the

following pictures

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