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

   The smallest gap felt as two touches. Fingertip: 3 mm. Palm: 11 mm. Forearm: 38 mm. Back: 60 mm. Esme says a fingertip and a forearm feel touch the same way because both are skin. Which statement is best supported?

   • The forearm is more sensitive than the palm, since 38 mm is a bigger gap than 11 mm is.
   • The back is the most sensitive, since 60 mm is the largest number in the whole table.
   • Fingertips are more sensitive: they feel two close touches that the forearm feels as one.
   • Each place feels touch the same, since each of them is made of skin.
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 sense organ moves the muscle directly without sending a signal.
   • In a reflex, the spinal cord sends the signal to the muscle, and the brain learns of it later.
   • 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.
4. 4.

   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 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.
   • 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.
5. 5.

   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 arms use a different brain, so the injury cannot affect signals to the legs.
   • 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 signals between the brain and the legs pass through the damaged part of the spinal cord.
6. 6.

   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?

   • Skin receptors respond less to a steady temperature, so the signals to the brain weaken.
   • 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.
7. 7.

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

   • Test the students five times each and record just the longest distance for each person in the group.
   • 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 students five times each but change the ruler and the starting hand each time.
8. 8.

   Ren wants to find out whether people respond more quickly to a sound or a sight. Which plan is best?

   • Test half the students with a sound signal and half with a sight signal, one trial each.
   • Test the students with a loud sound and a dim light, and compare how they respond.
   • Test the students with a sound signal first, then a sight signal, and compare their tiredness.
   • Test the same students with a sound and a sight signal, in random order, many times each.
9. 9.

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

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

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

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