Neurons and the main parts of the brain

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   A motor-neuron axon can be about 1 m long. Ari reads a card about three axons. An impulse travels the full 1 m length of axon Q. How long does that take?

   • 1 s
   • 20 s
   • 0.05 s
   • 0.02 s
2. 2.

   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?

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

3. 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

4. 3.

   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?

   • 13 ms
   • 3 ms
   • 10 ms
   • 30 ms
5. 4.

   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 temporal lobe; X is the parietal lobe
   • 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

6. 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.

7. 5.

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

   • The plan for the next finger movement
   • Feedback about how the movement is going
   • Orders that make the finger muscles contract
   • Memories stored by the cerebellum for the song
8. 6.

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

9. 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

10. 7.

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

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

11. 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

12. 8.

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

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

13. Notebook on the brain (model data)

    line	what it says
    1	The cerebrum handles thinking and planned movement
    2	The cerebellum helps with balance and coordination
    3	The brainstem links the brain to the spinal cord and helps keep breathing going
    4	The cerebellum stores long-term memories and makes decisions

14. 9.

    Pia reviews a notebook on three parts of the brain. Exactly one line is wrong. Which line, and why?

    • Line 4, because memory and decisions belong to the cerebrum
    • Line 3, because the brainstem handles memory instead of breathing
    • Line 1, because planned movement belongs to the cerebellum
    • Line 2, because the cerebellum is for thinking, not balance

15. 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.

16. 10.

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

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