Biology · Form and function
B3.3 — Muscle and motility
Biology · SL / HL · syllabus-mapped notes
B3.3.1
Adaptations for movement as a universal feature of living organisms
Explain movement as universal, considering one motile and one sessile species.
B3.3.2
Sliding filament model of muscle contraction
Explain how a sarcomere contracts by actin and myosin filaments sliding.
B3.3.3
Role of the protein titin and antagonistic muscles in muscle relaxation
Explain titin's role in recoil, and why muscles need antagonistic partners to lengthen.
B3.3.4
Structure and function of motor units in skeletal muscle
Describe the motor unit: the motor neuron, its muscle fibres, and the neuromuscular junctions.
B3.3.5
Roles of skeletons as anchorage for muscles and as levers
Explain how skeletons anchor muscles and act as levers, contrasting exoskeletons and endoskeletons.
B3.3.6
Movement at a synovial joint
Explain movement at the human hip joint, naming the femur and pelvis.
B3.3.7
Range of motion of a joint
Measure and compare a joint's range of motion in several dimensions.
B3.3.8
Internal and external intercostal muscles as an example of antagonistic muscle action to facilitate internal body movements
Explain how internal and external intercostal muscles act antagonistically to move the ribcage.
B3.3.9
Reasons for locomotion
Give four reasons for locomotion, with at least one example of each.
B3.3.10
Adaptations for swimming in marine mammals
Explain adaptations for swimming in marine mammals: streamlining, flippers, flukes and airways.