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

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

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

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

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

   After an injury, Jun's finger cannot bend, though the forearm muscle works well. A cut tendon is found. Why does this stop the finger?

   • The tendon holds the finger bones in a joint, so the joint cannot move without it.
   • The tendon is a muscle that bends the finger, so the finger has lost its own muscle.
   • The tendon joins the muscle to the finger bone, so the muscle's pull no longer reaches the bone.
   • The tendon joins one bone to another bone, so the finger bones come apart when the tendon is cut.
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 knee is a ball-and-socket joint but the knee bones are too weak to move in many ways.
   • 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).
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 ball-and-socket joint, which lets the head circle in any direction, as the shoulder does.
   • A pivot joint, where one bone turns around another, allows the head to turn.
   • A hinge joint, which lets the head bend forward and back but not turn from side to side.
   • A gliding joint, which lets the neck bones slide a little, but not turn.
7. 7.

   Noah twists an ankle, and the doctor says a ligament is stretched. What does a ligament do at a joint?

   • It joins one bone to another bone and helps hold the joint together.
   • It is the cushion of fluid between two bones that keeps them from rubbing.
   • It is a muscle that bends the joint when the nerve tells it to contract.
   • It joins a muscle to a bone and pulls on the bone when the muscle shortens.
8. 8.

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

   • High inside the nose, which send signals along a nerve to the brain
   • On the tongue, 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
9. 9.

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

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