Science Review 1

Science Review 1

Lessons 3.5 and 3.6

Bouncing Back

Bats may not seem to have much in common with whales and dolphins, but they do share an important ability-echolocation. Echolocation is the use of sound to hunt or to move around in areas of low light. 

Multiple Choice

What is echolocation?

• The use of sound to hunt or to move around in areas of low light.

• A sixth sense animals that have poor vision use to communicate.

• A secret form of communication between animals that humans cannot hear.

You've already learned that sounds are vibrations that travel through matter. Animals that use echolocation emit very high-pitched sounds. These sound waves bounce off objects in the animal's environment and send back echoes. The animal uses the echoes to locate prey. A bat, for example, can tell where an insect is, how large it is, and in what direction it is moving, even in complete darkness. A whale using echolocation to hunt may even be able to tell the difference between types of fish. 

Multiple Choice

What are sounds?

• Vibrations that travel through matter.

• Vibrations that can be perceived with the eye.

• A spectrum of colors that can be perceived with the nose.

Multiple Select

What kind of information can a bat get about a mosquito through echolocation?

• How big it is.

• Where it is.

• Where it is going

• How many wings it has.

• What kind of mosquito it is.

Multiple Choice

What is echolocation used for?

• To locate prey.

• To look for shelter.

• To communicate with animals of other species.

A sound's frequency, or number of vibrations per second, is measured in hertz. Human beings can hear sounds between about 20 and 20,000 hertz. The sounds that dolphins and whales use in echolocation vary from about 250 hertz to 220,000 hertz. Bats emit sounds between 20,000 and 120,000 hertz. Doesn't it seem like listening to sounds at such high frequencies would damage an animal's ears? As a form of protection, a muscle in the ear keeps the damaging pulses from being transmitted into the inner ear. 

Multiple Select

Which animals' echolocation sounds humans might be able to hear? (choose 2)

• dolphins

• whales

• bats

• sharks

It's probably hard to imagine that echoes could provide enough information for a bat to capture a tiny mosquito in the pitch-black night. Echolocators are very good, though, at interpreting the information they receive. The farther away an object is, the longer echoes take to come back. The echoes sound different, too, depending on the size of the object and its texture. 

Multiple Choice

What difference would distance make in echolocation?

• The farther the the object is the more it takes for the sound to bounce back

• Objects that are far away produce different sounds.

Feeling Nervous?

You may not realize it, but your nervous system is hard at work all the time. One of its jobs is to keep your body safe from harm. When you touch a hot pan, you quickly pull your hand away before you even realize what has happened. That's just a small part of what the nervous system does, though. It's in charge of all your body's actions and senses. Without it, you wouldn't be alive. 

Multiple Select

What's the function the nervous system?

• To make sure we touch dangerous things - like a hot pan

• To control all your body's actions and senses.

• To control some of your body's actions and senses.

There are two main parts to the nervous system. The central nervous system is made up of the brain and the spinal cord. The brain is the control center for your body. It uses the spinal cord to send out messages to the rest of the body. The peripheral nervous system is the huge network of nerves that runs from the spinal cord throughout your body. It carries impulses to and from the central nervous system. 

Multiple Select

What are the 2 main parts of the nervous system?

• The central nervous system.

• The peripheral nervous system

• The outer nervous system

• The inner nervous system.

Multiple Select

What is the central nervous system is made up of?

• brains

• spinal cord

• heart

• nerves

Multiple Choice

What does the peripheral nervous system do?

• It carries impulses to and from the central nervous system.

• It is in charge of the involuntary actions of the body.

• It is in charge of producing the brain's thoughts.

Neurons are the tiny cells that make up the tissues of the nervous system. There are billions of neurons in the human body. All sorts of things can stimulate neurons-an odor in the air, a flash of light, a math problem, taking a deep breath. When a neuron is stimulated, it reacts by sending an electrical impulse. This impulse causes chemicals called neurotransmitters to be released. They help the pulse travel to the next neuron, and so on. 

Multiple Choice

What happens when a neuron is stimulated?

• It reacts by sending an electrical impulse to the next neuron.

• It becomes dormant.

• It changes color for a few seconds.

Think of it as a chain reaction, like pushing a single domino and watching as a whole row of dominos tumble. The reaction continues until the message gets where it needs to go. It might reach a muscle and cause you to move your arm to flick away a bug by your face. It might reach your brain and be recorded as the smell of cookies baking. The nervous system helps you receive information from your environment and communicate it around your body. 

Multiple Select

What is the functions of the neurons' impulses?

• To help you receive information from your environment and communicate it around your body.

• To make you think about the sensations in your body.

• To help you carry out involuntary actions like breathing.