Body Systems and Senses — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. When you run, which system pulls on bones to move your legs?
A) Digestive system
B) Muscular system
C) Nervous system
D) Respiratory system
Muscles attached to bones contract and pull on them, creating the movement needed for running.
2. Which system gives your body its frame and supports your weight while running?
A) Skeletal system
B) Circulatory system
C) Digestive system
D) Endocrine system
The skeletal system provides structure, protects organs, and gives muscles solid points to pull against.
3. Which system speeds up to deliver more oxygen to leg muscles?
A) Skeletal system
B) Excretory system
C) Circulatory system
D) Skin
During running, the heart beats faster and arteries deliver more oxygen-rich blood to working muscles.
4. Which system brings in extra oxygen from the air while you run?
A) Digestive system
B) Nervous system
C) Muscular system
D) Respiratory system
Faster, deeper breathing pulls in more oxygen and removes more carbon dioxide as the body works harder.
Part B: Fill in the Blank
Write the correct answer on each line.
1. Running requires the muscular and skeletal systems to work together for movement.
Muscles need bones to anchor to so their pulling motion can move parts of the body.
2. The circulatory system delivers oxygen to muscles working hard during a run.
Working muscles need extra oxygen to keep producing the energy required for steady running.
3. Faster breathing during exercise shows the respiratory system working harder.
The respiratory system increases its rate to bring in more oxygen and release more carbon dioxide.
4. The nervous system sends signals from the brain to tell muscles when to move.
The brain and nerves send fast signals that tell muscles exactly when and how strongly to contract.
5. When body systems cooperate, they work as a team to keep you healthy and active.
No single system runs the body alone; each one supports the others so the whole body can function smoothly.