Joint — Science definition
A place where bones meet and movement is possible; its shape sets what movement is allowed — a hinge at the elbow, a ball and socket at the shoulder.
Where it is taught
- Bones, Muscles & Structure-Function Models — Body Organization, Transport & Movement, Life Science & Scientific Inquiry, Grade 7
In use
Every movement of a joint — the place where bones meet and motion is possible — is produced by one of a pair shortening while its partner lengthens.
Bones, Muscles & Structure-Function Models
Questions using joint
Problem 1
Answer and explanation
The strings represent pulls that can rotate the hinge in opposite directions, analogous to coordinated muscle actions. The model does not show nerves, living tissue, energy transfers, changing forces, or exact anatomical scale. It illustrates a mechanical relationship without establishing individual performance or health.
Identify the hinge as a turning point.
Connect each pull with an opposing action.
State missing tissues and cellular processes.
Response criteria
- Explain the relevant biological process accurately.
- Use the supplied evidence and show calculation steps with units where needed.
- Connect a labeled model or mechanism with the claim.
- State an assumption, evidence limitation, or useful next observation.
Problem 2
Answer and explanation
Skeletal muscle contraction produces a pull. Opposing muscle action or another force can restore the movement; relaxation is not an active push along the same attachment.
Response criteria
- Explain the relevant biological process accurately.
- Use the supplied evidence and show calculation steps with units where needed.
- Connect a labeled model or mechanism with the claim.
- State an assumption, evidence limitation, or useful next observation.
Problem 3
Answer and explanation
Nervous coordination is omitted; actual movement depends on signals controlling muscle actions. Cellular energy processes and living tissue properties are other valid examples.