[Campbell Biology P.988] Based on Table 42.1 'Comparing Air and Water as Respiratory Media' ... | Practice Question

Based on Table 42.1 'Comparing Air and Water as Respiratory Media' and the accompanying text, which of the following statements about respiratory media is/are TRUE? Select all that apply

  • A: Water is significantly denser and more viscous than air, making it harder for aquatic animals to move and force through respiratory surfaces.
  • B: At sea level, the partial pressure of O2 is the same in air and in water when equilibrium is reached, despite differences in O2 concentration.
  • C: Air has a much lower O2 concentration than water, requiring animals that breathe air to be highly efficient in O2 extraction.
  • D: The amount of dissolved O2 in water increases with higher temperature and salinity.

Explanation

Statement A is correct: Table 42.1 shows water is much denser 1 kg/L vs 0.0013 kg/L and more viscous 1 cP vs 0.02 cP than air, and the text explains this makes gas exchange more demanding for aquatic animals. Statement B is correct: The text explicitly states that 'water exposed to air at sea level has a PO2 of 160 mm Hg, the same as in the atmosphere.' Statement C is incorrect as air has a much higher O2 concentration 210 ml/L than water 7 ml/L . Statement D is incorrect as the text states that warmer and saltier water holds LESS dissolved O2.