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IB Biology HL B3.3 Muscle and Motility Hl Only Questions

Practise IB Biology HL B3.3 by linking sarcomere contraction and joint mechanics with ventilation, migration and marine-mammal swimming adaptations.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Identify muscle, fibre, myofibril and sarcomere organisation, then interpret Z-line and band changes as actin and myosin slide.
  • Trace motor-end-plate excitation and sarcoplasmic-reticulum calcium release to troponin binding and exposed actin sites.
  • Explain how ATP enables myosin detachment and reset during repeated cross-bridge cycling and sarcomere shortening.
  • Explain how titin centres myosin, recoils after stretching and limits sarcomere overstretching.
  • Apply contracting and relaxing antagonist pairs to predict flexion or extension in elbow and insect-joint diagrams.
  • Compare vertebrate endoskeletons with arthropod exoskeletons and use muscle attachments to explain support, lever action and movement.
  • Relate cartilage and synovial fluid to cushioning and low-friction movement, and distinguish tendon attachment from ligament stabilisation.
  • Compare hinge and ball-and-socket movement, then calculate range-of-motion changes from joint-angle or age-group data.
  • Explain how intercostal muscles move the ribs during inhalation or forced expiration and alter thoracic volume and pressure.
  • Interpret migration evidence and relate locomotion to seasonal access to food and suitable habitats.
  • Relate marine-mammal streamlining, flipper propulsion and tissue oxygen stores to swimming and dive-duration evidence.

Covered syllabus points

B3.3.1 (HL)—Movement adaptationsB3.3.2 (HL)—Sliding filament modelB3.3.3 (HL)—Titin and antagonistic musclesB3.3.4 (HL)—Motor unitsB3.3.5 (HL)—Skeletons as anchorage and leversB3.3.6 (HL)—Synovial joint movementB3.3.7 (HL)—Range of motionB3.3.8 (HL)—Intercostal musclesB3.3.9 (HL)—Reasons for locomotionB3.3.10 (HL)—Swimming adaptations in marine mammals

Question 1

[Maximum number: 2]

The bird known as the blackcap (Sylvia atricapilla) traditionally migrates from its summer breeding grounds in Central Europe to Spain and Portugal for the winter. State two adaptive advantages of bird migration.

Question 2

[Maximum number: 7]

The diagram shows a section through part of the leg of an insect and antagonistic muscles X and Y. The tibia moves in the direction shown by the arrow when the muscle is flexing.

Figure for Question 2 — IB Biology HL

Question (a)

(a)

Outline a reason for the muscles being described as antagonistic.

[ 1 ]

Question (b)

(b)

Describe the role of muscle Y.

[ 2 ]

Question (c)

(c)

Outline how the muscle attachment of insects differs from humans.

[ 1 ]

Question (d)

(d)

Explain the role of calcium ions in muscle contraction.

[ 3 ]
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