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

Grade 7 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   “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?

   • 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
   • The diaphragm sends the signal to the brain, and the brain follows it
   • The lungs make extra oxygen when the muscles ask for it

2. 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.

3. 2.

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

   • 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
   • brain → motor nerve → diaphragm → air pulled into the lungs
4. 3.

   At a swim lesson, Bo draws an air path: nose, trachea, stomach, lungs. Which statement finds the flaw?

   • The diaphragm should come before the nose to pull air in
   • Air goes from the trachea to the bronchi and lungs, not to the stomach
   • Breathed-out air should be carbon dioxide, so the path needs no oxygen
   • Oxygen should start in the lungs, because the lungs make it

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

   • Cell should come last, because it holds the most parts
   • There is no flaw, because organs and tissues are about the same size
   • Organ system should come first, because it contains the other levels
   • Tissue should come before organ, because organs are made of tissues
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. 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 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
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 spinal cord starts the pull-back, because a reflex does not wait for the brain
    • The brain starts the pull-back, because it must decide first
    • 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
    • Cell, tissue, organ, system, because each level is built from the one before
    • Cell, tissue, system, organ, because a system is just one small part of an organ
    • Tissue, cell, organ, system, because tissues hold the cells’ jobs