Neurons and the main parts of the brain

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Each axon is 0.6 m long. Bo compares two axons of the same length. How much sooner does the impulse arrive along axon T than along axon S?

   • 0.02 s sooner
   • 0.3 s sooner
   • 0.32 s sooner
   • 0.28 s sooner

2. Read this first

   Model path card (model data)

   measure	value
   Axon length	0.3 m
   Axon speed	30 m/s
   Chemical synapses on the path	3
   Delay at each chemical synapse	about 1 ms

3. 2.

   Esme adds up the time for a signal on this path. Count only the axon and the chemical synapses, using the delay on the card. What is the total?

   • 3 ms
   • 30 ms
   • 10 ms
   • 13 ms
4. 3.

   Ball-catch path (model, not to scale). Jun sees a ball coming and catches it. Which pair names lobe W and lobe X of the cerebrum?

   • W is the occipital lobe; X is the cerebellum, which plans the catch
   • W is the occipital lobe; X is the brainstem, which stores the plan
   • W is the occipital lobe; X is the frontal lobe
   • W is the temporal lobe; X is the parietal lobe

5. Piano loop (model, not to scale)

   The cerebrum sends a movement plan down the spinal cord to motor neurons, which reach the finger muscles. The cerebrum also sends a copy of the plan to the cerebellum. Sensory neurons from the fingers carry ? to the cerebellum.

6. 4.

   Kira practices the piano. What do the sensory neurons from the fingers carry to the cerebellum?

   • Orders that make the finger muscles contract
   • Memories stored by the cerebellum for the song
   • The plan for the next finger movement
   • Feedback about how the movement is going
7. 5.

   A gust of wind tips Luz's bike a little. Which sequence shows how the body corrects the tilt?

   • Sensory neurons report the tilt, the cerebellum compares it with the plan, motor neurons carry the fix
   • Motor neurons report the tilt, the cerebellum compares it with the plan, sensory neurons carry the fix
   • Sensory neurons report the tilt, the brainstem stores it as a memory, motor neurons carry the memory
   • Sensory neurons report the tilt, the cerebellum decides where to ride next, motor neurons carry the choice

8. Notebook on a chemical synapse (model data)

   line	what it says
   1	An electrical impulse runs along the axon to the axon terminals
   2	The axon terminals release neurotransmitter into the gap
   3	The electrical impulse then jumps across the gap into the next neuron
   4	The neurotransmitter binds to receptors on the next neuron

9. 6.

   Milo reviews a classmate's notebook on a chemical synapse. Exactly one line is wrong. Which line, and why?

   • Line 2, because chemicals cannot be released, so the impulse must cross
   • Line 1, because the axon carries chemicals, not impulses
   • Line 3, because chemicals, not the impulse, cross the gap
   • Line 4, because the chemicals should bind to the first neuron

10. Notebook on a reflex (model data)

    line	what it says
    1	A receptor in the skin starts the signal
    2	A sensory neuron carries the message out to the muscle
    3	An interneuron in the spinal cord links the sensory neuron to the motor neuron
    4	A motor neuron carries the message to the muscle

11. 7.

    Noah reviews a notebook on a reflex. Exactly one line is wrong. Which line, and why?

    • Line 3, because interneurons belong in the brain, not the spinal cord
    • Line 4, because motor neurons carry messages in from the muscle
    • Line 1, because the receptor is part of the muscle
    • Line 2, because sensory neurons carry messages in, not out to muscles

12. Use this

    Two claims (model data), 2 rows. Columns: claim, what it says. P, One electrical impulse keeps going from the first neuron into the next. Q, An electrical impulse runs along the axon, and chemicals carry the message across the gap.

13. 8.

    Ren compares two claims about a signal crossing a chemical synapse between two neurons. Which choice judges the claims correctly?

    • Both are right, since signals can move either way, forward or backward
    • Neither is right, since the axon carries chemicals and the gap carries electricity
    • Claim P is right: one electrical impulse keeps going from neuron to neuron
    • Claim Q is right: the impulse runs along the axon, and chemicals cross the gap

14. Use this

    Two claims (model data), 2 rows. Columns: claim, what it says. P, Sensory neurons carry messages from the skin to the spinal cord, and motor neurons carry messages from the spinal cord to muscles. Q, Motor neurons bring news in from the skin, and sensory neurons tell muscles what to do.

15. 9.

    Tala compares two claims about neuron types. Which choice judges the claims correctly?

    • Claim Q is right: motor neurons bring the news in, and sensory neurons order the move
    • Neither is right, since interneurons do the work of a reflex alone
    • Both are right, since neurons carry messages in either direction
    • Claim P is right: sensory neurons carry messages in, and motor neurons carry them out

16. Use this

    Two claims (model data), 2 rows. Columns: claim, what it says. P, The cerebellum does the thinking, and the brainstem stores memories. Q, The cerebrum does the thinking and holds memory, the cerebellum helps with balance, and the brainstem helps keep breathing going.

17. 10.

    Zee compares two claims about the main parts of the brain. Which choice judges the claims correctly?

    • Claim P is right: the little brain thinks, and the brainstem stores memories
    • Claim Q is right: the cerebrum thinks, the cerebellum balances, the brainstem helps breathing
    • Neither is right, since the three parts share the same jobs
    • Both are partly right: the brainstem stores memories, and the cerebellum helps breathing