plant responses part1
TRANSCRIPT
Plant Responses: Part 18SCIENCE: Wed. Feb. 16, Thurs. Feb.
17
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
Tropisms• Tropisms are responses of a
plant to an outside stimulus- Outside of an
organism- An example of an
inside stimulus would be the beating of your heart
We will learn about 3 types:• Thigmotropism• Phototropism• Gravitropism
Thigmotropism
• Thigma means touch in Greek
• If you touch 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