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 lungs sense the hill and speed up on their own without waiting for any signal
   • The brain sends signals along nerves that make the diaphragm contract faster
   • 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
   • Muscles work harder, so the lungs take in pure oxygen with each breath
   • 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

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

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?

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

   “A student's ladder, not to scale, read from the bottom step to the top step:” Jun’s ladder, from smallest to biggest, reads cell, organ, tissue, organ system. Which statement finds the flaw?

   • There is no flaw, because organs and tissues are about the same size
   • Tissue should come before organ, because organs are made of tissues
   • Organ system should come first, because it contains the other levels
   • Cell should come last, because it holds the most parts
8. 6.

   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?

   • Breathed-out air is carbon dioxide, so the sensor reading must be wrong
   • The lungs make fresh oxygen as the air leaves
   • Air breathed in has oxygen, and the body takes just part of it
   • The bag adds oxygen from the room to the breath
9. 7.

   “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 brain waits to feel the prick, then sends the move signal
   • The reflex signal turned around in the spinal cord, and the brain got the message after
   • The muscle feels the prick first and then tells the receptor
   • The motor nerve carries the prick feeling up to the brain
10. 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 diaphragm contracts, because that makes more room for air in the chest
    • The windpipe pushes air in, because it pumps air down toward the stomach first
    • The air sacs push air in, because they make oxygen to fill the lungs
    • The lungs pull air in, because they are muscles that squeeze
11. 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 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
    • The brain starts the pull-back, because it must decide first

12. 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.

13. 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