Stimuli lesson 3

1. Lesson 3: Stimuli Foundation Science SC 22101

2. Review Questions What is an external stimulus? Copy the word “PHOTOTROPIC” in your notebook. Underline the prefix, put a box around the suffix. What does phototropic mean? You see a bird dive down into the ocean. Guess what the external stimulus was to make the bird dive into the water like this.

3. Internal Stimulus Stimuli that are present inside of an organism are called internal stimuli. Stimulus - ? Response - ?

4. Internal Stimulus Stimuli that are present inside of an organism are called internal stimuli. Stimulus - hunger Response – look for food Body then back more toward homeostasis

5. Internal Stimulus We don’t see, hear, smell, touch or taste internal stimuli. Examples of internal stimuli: -Headache -Being thirsty -Being hungry

6. Internal or External? A fever is usually a reaction to an internal stimulus. Stimulus = too many bacteria in your body Response = body makes itself hot to kill bacteria (most bacteria die if they get too hot)

7. Questions Label internal or external stimulus: -You see a spider and scream. -You have a stomach ache and decide to lay down. -A bird is thirsty and drinks some water. -A squirrel sees a cat and runs up a tree. -A lion gets hungry and eats a gazelle. 2. If an organism is not in homeostasis, it will probably be motivated to find food or water by ____________ stimuli. 3. True or False: bacteria respond to internal and external stimuli. 4. Sea anemones catch fish by using their sticky tentacles. What stimuli do the sea anemones respond to in order to catch the fish? External or internal?