Bones, muscles and the senses

Grade 7 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   Ari bends an elbow to lift a book. Which muscle contracts, and which relaxes?

   • The triceps contracts and pulls the forearm up, while the biceps relaxes and lets it go.
   • The biceps and the triceps both contract at the same moment to move the forearm.
   • The biceps contracts and pulls the forearm up, while the triceps relaxes.
   • The biceps and the triceps both relax so that the forearm can swing up by itself.
2. 2.

   Bo asks why one muscle cannot both bend and straighten the elbow. What is the best answer?

   • A muscle only pulls when it contracts, so a second muscle on the other side pulls the bone back.
   • Ligaments decide which way a bone moves, so one muscle can bend and straighten it alone.
   • Bones bend and straighten themselves, and the muscles only hold the bones together tightly.
   • Muscles push bones into place, so one muscle is enough if it pushes the bone the other way each time.
3. 3.

   Esme kicks a ball and the knee straightens. Which muscle group contracts to straighten it?

   • The hamstrings on the back of the thigh, which push the lower leg out straight ahead.
   • The calf muscle at the back of the lower leg, which holds the knee tightly in place.
   • The quadriceps on the front of the thigh, which pulls the lower leg forward.
   • The hamstrings on the back of the thigh, which bend the knee and pull the lower leg back.
4. 4.

   Kira studies a joint that only bends and straightens, like a door hinge. Which joint type is it?

   • A joint that fuses, like the skull bones, which does not move.
   • A pivot joint, like the neck, which turns from side to side.
   • A ball-and-socket joint, like the shoulder, which moves in many directions.
   • A hinge joint, like the elbow or the knee, which moves in one direction.
5. 5.

   Luz swings an arm in a full circle but cannot do that with a leg at the knee. What explains the difference?

   • The shoulder is a hinge joint, which moves in many directions, and the knee is a pivot joint.
   • The shoulder has more ligaments than muscles, so it can turn right around.
   • The shoulder is a ball-and-socket joint (many ways); the knee is a hinge (one way).
   • The knee is a ball-and-socket joint but the knee bones are too weak to move in many ways.
6. 6.

   Milo turns the head left and right to look both ways. Which joint type at the top of the neck allows this?

   • A gliding joint, which lets the neck bones slide a little, but not turn.
   • A pivot joint, where one bone turns around another, allows the head to turn.
   • A ball-and-socket joint, which lets the head circle in any direction, as the shoulder does.
   • A hinge joint, which lets the head bend forward and back but not turn from side to side.
7. 7.

   Pia smells fresh bread from across the room. Where are the receptors that detect the smell?

   • On the tongue, which send signals along a nerve to the brain
   • High inside the nose, which send signals along a nerve to the brain
   • In the brain, which detect the smell and then tell the nose about it
   • In the lungs, which send signals along a nerve to the brain
8. 8.

   Ren learns that touch receptors are more crowded on fingertips than on the back. What does that mean for what each place can feel?

   • Fingertips can tell two close touches apart, but the back may feel them as one touch.
   • The back can tell two close touches apart better, because it is a larger area of skin.
   • Fingertips feel less than the back, because crowded receptors block each other's signals.
   • Both places feel two close touches the same way, because skin everywhere has receptors.
9. 9.

   Tala tastes a slice of lemon and puckers up. Which pair names the stimulus and the response?

   • Stimulus: the tongue. Response: chemicals in the lemon juice and a sour taste.
   • Stimulus: a sour taste. Response: chemicals in the lemon juice reaching the tongue.
   • Stimulus: chemicals in the lemon juice. Response: a sour taste and a pucker.
   • Stimulus: the pucker of the face. Response: chemicals in the lemon juice.
10. 10.

    Zee notices a strong smell in a room, but after ten minutes hardly notices it. What best explains this?

    • The smell is used up in the air, so there is less of it left for the nose to detect in the room.
    • The receptors wear out for the whole day and cannot be used again until the next morning comes.
    • Receptors respond less to a steady smell, so the brain gets weaker signals and it seems to fade.
    • The brain turns off the nose after ten minutes, whatever the smell may be, to save energy.