The breathing and nervous systems, and how a signal reaches the brain

Grade 7 Science Worksheet

Circle the best answer.

1. Read this first

   Levels ladder, not to scale

   Four steps from the smallest piece at the bottom to the biggest group at the top. Part | letter | job: cell | W | the smallest unit of life; tissue | X | a group of similar cells that do one job; organ | Y | several tissues working together as one body part; organ system | Z | several organs working together on a big job.

2. 1.

   A lung is made of several kinds of tissue that work together to move air and let oxygen pass. Luz places the lung on a levels ladder. Which level is it?

   • A cell, because it holds the tiny air sacs
   • An organ, because it joins several tissues
   • A tissue, because it is made of cells
   • An organ system, because it takes in air
3. 2.

   The nose, windpipe, bronchi and lungs work together to bring in oxygen. Noah adds this whole group to the levels ladder. Which level is it?

   • An organ, because it is one large body part
   • A cell, because living things have cells
   • An organ system, because several organs work together
   • A tissue, because it is made of cells
4. 3.

   “Breathing drawing, not to scale:” Before a choir song, Pia breathes in. Air reaches the alveoli. What happens to the oxygen there?

   • It is made there from the carbon dioxide that arrives
   • It passes into the capillaries and is carried to body cells
   • It moves on down a tube into the stomach
   • It is used up in the air sacs, so no oxygen is breathed out

5. Breathing drawing, not to scale

   a chest outline with the air path inside. Letters: Y is the lungs. Numbered path: 1 nose or mouth, 2 trachea, 3 bronchi, 4 lungs, 5 alveoli. Air-mix card: air breathed in is about 21% oxygen.

6. 4.

   Ren sings in choir and breathes in and out. Air breathed in is about 21% oxygen. Which statement compares it with the air breathed out?

   • Breathed-out air has more oxygen, because the lungs make extra
   • Breathed-in air is oxygen, and breathed-out air is carbon dioxide
   • Both are the same mix, because the lungs just move air around
   • Breathed-out air has less oxygen and more carbon dioxide
7. 5.

   “Breathing drawing, not to scale” Tala sings a long note and then takes a quick breath in. Which action pulls air into the lungs?

   • The windpipe pumps air down toward the stomach
   • The diaphragm contracts and makes more room in the chest
   • The air sacs make fresh oxygen that fills the lungs
   • The lungs squeeze themselves and pull air in
8. 6.

   “Nervous-system drawing, not to scale: a body outline with the signal path inside. Parts shown:” Zee sees a ball coming. Which path carries the signal from the eye to the arm muscles?

   • receptor → sensory nerve → muscle → motor nerve → brain
   • receptor → motor nerve → brain → sensory nerve → muscle
   • receptor → sensory nerve → brain → motor nerve → muscle
   • receptor → sensory nerve → brain → sensory nerve → muscle
9. 7.

   “Nervous-system drawing, not to scale:” In a ball catch, a motor nerve reaches Ari’s arm muscle. In which direction does a signal travel along that motor nerve?

   • From the muscle toward the brain, like a sensory nerve
   • From the brain out toward the muscle
   • Back and forth, bouncing between brain and muscle
   • From the eye toward the brain, as the receptor sends it

10. Use this

    Nervous-system drawing, not to scale: a body outline with the signal path inside. Parts shown: receptor, sensory nerve, spinal cord, brain, motor nerve. The receptor is in the skin of the fingertip.

11. 8.

    Bo touches a cold window and notices the chill. Which path carries that message from the skin to the brain?

    • brain → spinal cord → sensory nerve → receptor in the skin
    • receptor in the skin → motor nerve → spinal cord → brain
    • receptor in the skin → sensory nerve → spinal cord → brain
    • receptor in the skin → sensory nerve → brain → spinal cord
12. 9.

    “not to scale” After Jun pulls a hand back from an icy window, Jun’s brain learns what happened. How does the brain find out?

    • The motor nerve carries a report back from the muscle to the brain
    • The brain is not told, because the spinal cord handles the signal alone
    • The brain sent the signal that moved the hand, so it already knew about it
    • Another signal travels up the spinal cord, so the brain learns after the move
13. 10.

    Kira compares two actions: pulling a hand back from an icy window, and choosing which window to touch. What is different about the brain’s job?

    • The choosing skips the brain’s decision, but the pull-back needs it
    • Both wait for the brain to decide before the muscle moves
    • The pull-back skips the brain’s decision, but the choosing needs it
    • Both skip the brain, because the muscles do the work