Nature of science:

Developments in scientific research follow improvements in apparatus—fluorescent calcium ions have been used to study the cyclic interactions in muscle contraction. (1.8)

• Bones and exoskeletons provide anchorage for muscles and act as levers.
• Synovial joints allow certain movements but not others.
• Movement of the body requires muscles to work in antagonistic pairs.
• Skeletal muscle fibres are multinucleate and contain specialized endoplasmic reticulum.
• Muscle fibres contain many myofibrils.
• Each myofibril is made up of contractile sarcomeres.
• The contraction of the skeletal muscle is achieved by the sliding of actin and myosin filaments.
• ATP hydrolysis and cross bridge formation are necessary for the filaments to slide.
• Calcium ions and the proteins tropomyosin and troponin control muscle contractions.

Applications and skills:

• Application: Antagonistic pairs of muscles in an insect leg.
• Skill: Annotation of a diagram of the human elbow.
• Skill: Drawing labelled diagrams of the structure of a sarcomere.
• Skill: Analysis of electron micrographs to find the state of contraction of muscle fibres.

• Aim 7: Use of grip strength data loggers to assess muscle fatigue.
• Aim 7: Use of animations to visualize contraction.

• Elbow diagram should include cartilage, synovial fluid, joint capsule, named bones and named antagonistic muscles.
• Drawing labelled diagrams of the structure of a sarcomere should include Z lines, actin filaments, myosin filaments with heads, and the resultant light and dark bands.
• Measurement of the length of sarcomeres will require calibration of the eyepiece scale of the microscope.