Body Systems and Senses — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
The pupil are the white part of the eye that protects the inside.
Corrected: The pupil is the dark opening that lets light into the eye.
The pupil is an opening surrounded by the iris that adjusts in size to control how much light enters the eye.
2. Fix the sentence:
The retina sit at the front of the eye and bends light rays.
Corrected: The retina sits at the back of the eye and detects light signals.
The retina contains light-sensitive cells that turn light into nerve signals sent to the brain through the optic nerve.
3. Fix the sentence:
The eardrum vibrate when light waves hit it inside the outer ear.
Corrected: The eardrum vibrates when sound waves hit it inside the middle ear.
The eardrum is a thin membrane that vibrates from sound waves and passes those vibrations to tiny bones in the middle ear.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. Light enters the eye through an opening called the pupil in the center of the iris.
The pupil widens in dim light and narrows in bright light to control how much light reaches the retina.
2. The lens of the eye focuses light onto the back of the eye.
The lens changes shape to focus light from near or far objects onto the retina for sharp vision.
3. Sound waves cause the eardrum to vibrate inside the ear canal.
The eardrum vibrates and passes sound vibrations to small bones that send signals deeper into the ear.
4. The inner ear holds tiny bones and the cochlea that turn vibrations into nerve signals.
The inner ear contains the cochlea, which converts sound vibrations into electrical signals for the brain.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. What is the job of the retina in the eye?
Sample answer: The retina sits at the back of the eye and detects light, turning it into signals the brain can understand as images.
The retina is full of rods and cones that respond to light and color, sending information through the optic nerve to the brain.
2. How does the outer ear help us hear sounds?
Sample answer: The outer ear collects sound waves and funnels them down the ear canal toward the eardrum.
The curved shape of the outer ear gathers sound waves and directs them inward so they can vibrate the eardrum.