Many Terrestrial Arthropods Exchange Gases with Their Environments by Using

question 18

Multiple Choice

Many terrestrial arthropods exchange gases with their environments by using tracheae, tubes that lead from openings (called spiracles) in the animal's exoskeleton or cuticle directly to the animal's tissues. Some arthropods can control whether their spiracles are opened or closed; opening the spiracles allows the carbon dioxide produced in the tissues to travel down the tracheae and be released outside the animal. Klok et al. measured the carbon dioxide emitted over time (represented by VCO₂) by several species of centipedes. The figures present graphs of their results for two species, Cormocephalus morsitans and Scutigerina weberi. (C. J. Klok, R. D. Mercer, and S. L. Chown. 2002. Discontinuous gas-exchange in centipedes and its convergent evolution in tracheated arthropods. Journal of Experimental Biology 205:1019-29.) Copyright 2002 The Company of Biologists and the Journal of Experimental Biology.
Look at the graph for Scutigerina weberi (note the scale of the y-axis) in the figure.
-How would a terrestrial centipede most likely benefit from the ability to close its spiracles? Closing spiracles would ________.

• A) allow the centipede to move more quickly
• B) allow the centipede to retain more moisture in its tissues
• C) allow the centipede to stay warmer
• D) allow more oxygen from the environment to reach the centipede's tissues

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