1. Responses of Living Things
Mrs. Walker
4th Grade
Chapter 4

2. THINK-PAIR- SHARE
A bloodhound sniffs the ground, following a scent. A tree grows tall, reaching toward the sunlight. A child covers his ears after hearing a loud noise.
THINK: What do the bloodhound, the tree, and the child have in common? You will have one minute to discuss this with your partner. Then we will share our opinions.

3. THINK-PAIR-SHARE
The bloodhound, the tree, and the child are all reacting to things in their surroundings.
Look at the chart. Tom is reacting to his surroundings.
Cause:
Effect:
Sarah screamed very loudly.
Tom covered his ears after hearing a loud noise.

4. Reacting to the Environment
All living things react to their surroundings, or environment. In Chapter 1 we learned about life processes, and when an organism react to their environment, they are carrying out life processes. The environment is everything that surrounds a living thing.

5. How do you detect changes in your environment?
Using the Senses
How do you detect changes in your environment?
The Five Senses:
You use your sense organs such as your eyes, nose, ears, and skin.
You use your eyes to see, your nose to smell, your ears to hear, and your skin to touch. Special parts of your tongue help you taste the food you eat.

6. Reacting to the Environment
Imagine that you feel a cold wind outside. What would be your reaction? Your reaction would be putting on a sweater or a jacket.
A stimulus is anything that causes a living thing to react.
A reaction to a stimulus is called a response. Shivering and putting on a sweater are responses.

7. Reacting to the Environment
Many animals use the five senses to detect stimuli and respond. Rabbits use their good sense of hearing to detect enemies and respond by scurrying to their dens. Plants do not have five senses, but they do react to stimuli. Plants grow toward light.

8. Other Sense Organs
Have you ever heard the phrase “ blind as a bat”?
Bats can see, but most do not see well. Some bats do not see well. Some bats do not use their eyes to find juicy moths to eat. Instead, these bats send out sound waves that bounce off objects in the environment and travel back to the bats. This form of detection is called echolocation. Dolphins also use echolocation.

9. Bats
Watch Tim and Moby explain everything you need to know about bats!

10. Other Sense Organs
Another example of animals using their sense organs is the crayfish. Crayfish have hairs that can detect tiny movements in the water around them. This helps them find food.
Crickets have hearing organs on their legs! Bees can taste with their antennas. They also have organs for taste on their jaws and on their front legs.

11. Other Sense Organs
Some animals sense things in unusual ways. You may have seen a snake flicking its forked tongue back and forth. The snake is using its tongue and an organ in its mouth to smell. The tongue takes in particles of scent from the air. The tongue then transfers the particles to the organ in the snake’s mouth. The organ analyzes the particles.

12. External and Internal Stimuli
Anything in an organism’s environment that causes it to react is an external stimulus. Bright sunlight is an external stimulus for most plants. The plants grow toward the light.
An internal stimulus is anything within an organism that causes it to react.
For example, hunger pains are an example of an internal stimulus. For most people, the reaction to this stimulus is to eat.

13. External and Internal Stimuli
Plants and animals react to both external and internal stimuli. Some dogs respond to the sight and sound of a can of dog food being opened by salivating. The sight of the dog food can and the sound of it being opened are external stimuli.

14. How Do Living Things Detect Stimuli?:
Classify the following statements as a Cause or Effect on your graphic organizer.
A cold wind blows on you
The plant wilts
You shiver and put on a sweater
A plant needs water
The dog salivates
A moth detects a bat’s sound waves
A dog sees a can of its food being opened
The moth flies away, flies in loops, or drops to the ground and hides.
****Check your answers on the next slide.

15. How Do Living Things Detect Stimuli?
Cause
Effect
A cold wind blows on you
You shiver and put on a sweater
A plant needs water
The plant wilts
A moth detects a bat’s sound waves
The moth flies away, flies in loops, or drops to the ground and hides.
A dog sees a can of its food being opened.
The dog salivates

16. Review Questions:
Use pages A90-A94 to help answer your review questions.