1. Plant Responses: Part 1 8SCIENCE: Wed. Feb. 16, Thurs. Feb. 17

2. 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

4. An example of an inside stimulus would be the beating of your heartWe will learn about 3 types: Thigmotropism Phototropism Gravitropism

5. 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

6. 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

7. Gravitropism Response of a plant to gravity Plants with roots growing downwards is called positivegravitropism If plants have a stem growing upwards, it is called negativegravitropism Click to see animation