This document discusses plant responses and different types of tropisms. It defines a stimulus as anything in the environment that changes an organism's behavior. It provides examples of plant stimuli like light, temperature, water, and gravity. The document then explains that tropisms are plant responses to outside stimuli and lists three types - thigmotropism, phototropism, and gravitropism. It provides a brief definition and example of each tropism type.

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