Bones, muscles and the senses

Grade 7 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Ari says the eyes do all the seeing and the brain only stores pictures. Which case best argues against this?

   • A person with healthy eyes sees clearly, which shows the brain has no job in sight.
   • A person with healthy eyes cannot see after damage to the visual part of the brain.
   • A person who wears glasses sees better, which shows the lens does the seeing.
   • A person with a damaged eye can still see a little, which means the eye is not needed.
2. 2.

   10 students named the flavor of a jelly bean. Nose open: 9 right. Nose pinched shut: 3 right. Bo says taste alone tells the flavor of a jelly bean. What does the test best show?

   • Pinching the nose made tongue receptors stop working, so taste was lost for the test.
   • Smell adds a lot to flavor, since pinching the nose cut right answers from 9 to 3.
   • Smell is the main sense in flavor, since 3 students were right with a nose pinched.
   • Taste alone gives the flavor, since the tongue was used in both tests.
3. 3.

   Jun says a reflex happens in the brain first, so it needs thinking. Which fact best argues against this?

   • In a reflex, the signal goes to the brain first, which decides within a second whether to move.
   • In a reflex, the muscle moves by itself with no signal from a nerve at any stage.
   • In a reflex, the spinal cord sends the signal to the muscle, and the brain learns of it later.
   • In a reflex, the sense organ moves the muscle directly without sending a signal.
4. 4.

   Kira's ankle is swollen and sore after a fall. An X-ray shows no broken bone. Which cause fits best?

   • A tendon joined bone to bone and has torn, which an X-ray of bone would show.
   • A muscle pushed the bone out of place, which an X-ray of bone would show clearly and quickly.
   • A ligament at the joint was stretched or torn, which an X-ray of bone would not show.
   • The joint has no fluid left, so a break must be hidden behind the swollen skin.
5. 5.

   Luz reads about a person whose eardrum and three small bones work well but who hears nothing. Which problem best explains it?

   • Damage to the eardrum stops the vibration, since the eardrum is the first part of the path.
   • Damage to the three small bones stops the vibration, since they pass it to the eardrum.
   • Damage to the outer skin of the ear stops the sound, since that skin carries the signal.
   • Damage in the cochlea or the auditory nerve stops the signal from reaching the brain.
6. 6.

   Milo reads about a person with an injury low on the spinal cord: both arms feel and move, but the legs do not. Which explanation fits best?

   • The brain cannot feel the legs, so the leg muscles are no longer joined to bones by tendons.
   • The leg bones were damaged, so the brain can no longer send signals to any muscles.
   • The arms use a different brain, so the injury cannot affect signals to the legs.
   • The signals between the brain and the legs pass through the damaged part of the spinal cord.
7. 7.

   Noah puts a hand in warm water, and after a minute the water feels less warm. The thermometer reads the same. What best explains this?

   • The hand warmed up to match the water, so the receptors can no longer feel any change.
   • The water cooled down, so the receptors correctly report a lower temperature than before.
   • The brain forgets the temperature, so the receptors stop sending signals altogether.
   • Skin receptors respond less to a steady temperature, so the signals to the brain weaken.
8. 8.

   Pia wants to test whether practice makes reaction time quicker with the ruler drop. Which plan is best?

   • Test students five times each but change the ruler and the starting hand each time.
   • Test one student once, then test a different student after ten tries and compare them.
   • Test the same students five times, with the same ruler and method, recording each distance.
   • Test the students five times each and record just the longest distance for each person in the group.
9. 9.

   Tala wants to test whether pupils get wider in dim light. Which plan is best?

   • Measure the same person's pupils in a bright room, then a dim room, with the same camera.
   • Measure the same person's pupils in a dim room alone, and compare them with a drawing.
   • Measure one person's pupils in a bright room and another person's pupils in a dim room.
   • Measure the same person's pupils in a bright room and in a dim room, but change the camera.
10. 10.

    Zee compares two reaction studies. Which study gives the stronger evidence that practice helps?

    • Study 1, because it used different rulers, which makes the results more varied and more real.
    • Study 1, because it was shorter, so the students stayed fresh through all of the tries.
    • Study 2, because it has more students and tries, and every test was done the same way.
    • Neither, because a study about reaction cannot be used as evidence for anything.