Q18 - Surface-to-Volume Scaling Explains Animal Body Proportions

Theoretical B Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Archibald Hill (1886-1971) invented the field of biophysics, which can use simple geometric equations to predict how the anatomy of large and small animals differs. (1) Organisms exchange substances across a surface area. These substances are used to supply a volume of tissue. (2) The maximum force a muscle can generate is proportional to the number of muscle fibres contracting in parallel. (3) The maximum force a column can withstand is proportional to its cross-sectional area.

Figure 1 for Q18: Surface-to-Volume Scaling Explains Animal Body Proportions

Using the information and data, determine which of the statements are true or which are false.

A. Increasing an organism's mass 8 times approximately halves its surface area to volume ratio.

B. Diffusion rates are more likely to be inadequately low for large animals than small animals.

C. Larger animals can carry heavier objects, compared to their body weight, than small animals.

D. A cat's (Felis silvestris catus) bones are disproportionately thick, as a ratio of their body size, when viewed alongside an elephant's (Elephantidae) skeleton.

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Question reproduced from IBO 2017, Theoretical Exam B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions