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Plant Responses: Part 1. What are plant responses?. All living organisms will respond to a stimulus, including plants A stimulus is anything in the environment that changes an organism’s behavior - PowerPoint PPT Presentation
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Plant Responses: Part 1
What are plant responses?• All living organisms will respond to a stimulus,
including plants• A stimulus is anything in the environment that
changes an organism’s behavior– Example: If you are sitting in a dark room watching a movie and
you hear the telephone ring, you may jump. You have just responded to the stimulus by changing your behavior!
• Examples of plant stimuli: light, temperature, amount of water, gravity
TropismsTropisms are responses of a plant to an outside stimulus• Outside of an
organism
We will learn about 3 types:• Thigmotropism• Phototropism• Gravitropism
Thigmotropism
• Thigma means touch in Greek
• If something touches certain plants, this changes the plant’s behavior
• E.g. in a pea plant, if something touches one of its stems/leaves, it will wrap itself around something
Phototropism• When a plant responds to light: a plant will
bend towards the light • If a plant is growing towards light, it is called
positive phototropism– If it is growing away from the light, it is called
negative phototropism
Gravitropism
• Response of a plant to gravity• Plants with roots growing downwards is called positive
gravitropism– If plants have a stem growing upwards, it is called negative
gravitropism
– Click to see animation