Body Systems and Senses — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Which body systems work together when you run after a ball?
A) Only the muscular system
B) Nervous, muscular, skeletal, respiratory, and circulatory systems
C) Only the digestive system
D) Only the nervous system
Grade 4 science shows that running uses many systems together: nerves signal muscles, bones move, lungs and heart work harder.
2. When you smell cookies and your mouth waters, which systems are working together?
A) Skeletal and muscular only
B) Nervous and digestive systems
C) Respiratory and skeletal only
D) Circulatory and skeletal only
Grade 4 students learn the nervous system senses smell and signals the digestive system to make saliva.
3. Which statement about reflexes is correct in Grade 4 science?
A) Reflexes happen only after the brain finishes thinking
B) Reflexes can act through the spinal cord before the brain processes the event
C) Reflexes use only bones
D) Reflexes only happen in the ears
Grade 4 science teaches that reflexes can use the spinal cord as a shortcut so the body responds quickly.
4. Why do scientists say the brain is the most important part of using our senses?
A) It moves bones directly
B) It interprets signals from sense organs into useful information
C) It pumps blood to the eyes
D) It produces saliva
In Grade 4 science, the brain interprets nerve signals so we recognize sights, sounds, smells, tastes, and touches.
Part B: Fill in the Blank
Write the correct answer on each line.
1. A signal from the eye travels along the optic nerve to reach the brain.
Grade 4 students learn the optic nerve carries signals from the eye to the brain so we can see.
2. Your heart beats faster during exercise because the muscular system needs more oxygen.
Grade 4 science explains that the muscular system needs more oxygen during exercise, so the heart pumps faster.
3. When you hear a loud noise, your ears detect sound waves and send signals to the brain.
Grade 4 students learn the ears collect sound waves and send signals to the brain through nerves.
4. The circulatory system carries oxygen-rich blood from the lungs to all body cells.
Grade 4 science teaches the circulatory system delivers oxygen from the lungs to every cell in the body.
5. Working together, sense organs, nerves, the brain, and muscles let the body sense, decide, and respond to the world.
In Grade 4 science, sensing, processing, and responding form the cycle that keeps the body safe and active.