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

Grade 7 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Tala pedals up a hill and breathes faster. The figure shows the nervous and breathing systems. Which sentence explains how they work together?

   • The brain sends signals along nerves that make the diaphragm contract faster
   • The lungs sense the hill and speed up on their own without waiting for any signal
   • The diaphragm sends the signal to the brain, which then speeds up
   • The brain tells the lungs to make more oxygen for the muscles
2. 2.

   “Two drawings, not to scale:” Zee’s class records breathing at rest and on a bike. Use the table and both systems to explain the change. Which explanation fits?

   • The lungs make extra oxygen when the muscles ask for it
   • The diaphragm sends the signal to the brain, and the brain follows it
   • Working muscle cells give off more carbon dioxide, so the brain signals the diaphragm to contract faster
   • Muscles work harder, so the lungs take in pure oxygen with each breath

3. Read this first

   Two drawings, not to scale

   a breathing path and a nervous-system path. Parts shown: brain, motor nerve, diaphragm, lungs. Choices are paths that start with a part and end with air or oxygen.

4. 3.

   Ari rides fast, and the brain speeds up breathing. Which path joins the nervous system to the breathing system?

   • brain → motor nerve → diaphragm → air pulled into the lungs
   • diaphragm → sensory nerve → brain → air pulled into the lungs
   • brain → motor nerve → stomach → air pulled in
   • brain → motor nerve → lungs → oxygen made for the body

5. Use this

   Nervous-system drawing, not to scale: a body outline with the signal path inside. Parts shown: receptor, sensory nerve, brain, motor nerve, muscle. Esme's drawing of a reflex.

6. 4.

   Esme draws the pinecone reflex path: receptor, sensory nerve, brain, motor nerve, muscle. Which statement finds the flaw?

   • A reflex path turns around in the spinal cord, not in the brain
   • The receptor should sit in the muscle, not in the skin
   • The motor nerve should carry the signal toward the brain
   • There is no flaw, because the brain must decide before any movement
7. 5.

   Read-about card: an adult holds the bag; the sensor reads some oxygen in the breathed-out air. At a swim lesson, Kira breathes out once into a clear bag. A sensor still finds oxygen in the bag. How can that be?

   • Air breathed in has oxygen, and the body takes just part of it
   • The lungs make fresh oxygen as the air leaves
   • The bag adds oxygen from the room to the breath
   • Breathed-out air is carbon dioxide, so the sensor reading must be wrong
8. 6.

   “not to scale” Luz brushes a prickly pinecone and pulls a hand back, then feels the prick a moment later. Why does the feeling come after the move?

   • The muscle feels the prick first and then tells the receptor
   • The reflex signal turned around in the spinal cord, and the brain got the message after
   • The brain waits to feel the prick, then sends the move signal
   • The motor nerve carries the prick feeling up to the brain

9. 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.

10. 7.

    Milo reads that nervous tissue carries signals in the brain, yet the brain is called an organ, not a tissue. Why?

    • The brain is an organ system, since it controls the whole body
    • A tissue is a bigger level than an organ, so the brain fits the smaller one
    • An organ is one kind of cell, so the brain counts as one
    • An organ joins nervous tissue with other tissues that work together
11. 8.

    Breathing drawing, not to scale. Before a swim lesson, Pia and a teacher talk about how air gets into the lungs. Which claim with its reason is better?

    • The lungs pull air in, because they are muscles that squeeze
    • The diaphragm contracts, because that makes more room for air in the chest
    • The air sacs push air in, because they make oxygen to fill the lungs
    • The windpipe pushes air in, because it pumps air down toward the stomach first
12. 9.

    Nervous-system drawing, not to scale: a body outline with the signal path inside. Ren and a teacher compare ideas about the pinecone reflex. Which claim with its reason is better?

    • The brain starts the pull-back, because it must decide first
    • The spinal cord starts the pull-back, because a reflex does not wait for the brain
    • The motor nerve starts the pull-back, because it carries signals in
    • The muscle starts the pull-back, because it feels the prick itself

13. Use this

    Four level cards, not to scale, shown in no order. Part | letter | job: organ | W | several tissues working together as one body part; cell | X | the smallest unit of life; organ system | Y | several organs working together on a big job; tissue | Z | a group of similar cells that do one job.

14. 10.

    Noah sorts nerve cell, nervous tissue, brain and nervous system onto a ladder. Which order with its reason is better?

    • Cell, organ, tissue, system, because an organ is simpler than a tissue
    • Tissue, cell, organ, system, because tissues hold the cells’ jobs
    • Cell, tissue, system, organ, because a system is just one small part of an organ
    • Cell, tissue, organ, system, because each level is built from the one before