IB Biology HL B3.3 Muscle and motility questions

Exam-style multiple choice and written questions with full markschemes. Check multiple choice answers straight away, or type, photograph or draw a written answer and get it marked.

Question 1

Multiple choiceMedium1 mark

An arthropod and a vertebrate each move an appendage when a skeletal muscle contracts. Which comparison correctly describes how their skeletons contribute?

Show answer and explanation

Answer: C. Arthropods have exoskeletons, while vertebrates have endoskeletons. Arthropod muscles attach to the inner surface of the exoskeleton, whereas vertebrate muscles attach to bones. When muscles contract, the skeleton provides anchorage and acts as a lever to move the appendage.
A: reverses which group has an exoskeleton and which has an endoskeleton.
B: places the arthropod muscle attachment on the outer, rather than inner, surface of the exoskeleton.
D: reverses the roles: the skeleton acts as the lever, while muscles provide the force.
Remember: skeletons provide muscle anchorage and act as levers during movement.

Question 2

Paper 2Medium16 marks

A field team records three consecutive dive cycles of a bottlenose dolphin. Each cycle consists of one dive followed by a surface interval. No breaths are observed during dives; at least one breath is observed during each surface interval.

Dive cycleTime underwater / minSurface interval for breathing / min
14.00.5
25.00.5
33.00.5
(a)

Describe the pattern in the timing of the dives and surface intervals, using data from the table.

[2]
(b)

Calculate the percentage of the total observation time that the dolphin spends underwater.

[3]
(c)

Explain how the dolphin’s body shape, limbs and tail are adapted for swimming. Include the direction of tail movement.

[6]
(d)

Explain how airway adaptations allow the dolphin to breathe in the pattern recorded.

[5]

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