[Campbell Biology P.1227] Which statement correctly describes the seasonal changes in a lake ... | Practice Question

Which statement correctly describes the seasonal changes in a lake with winter ice cover as depicted in Figure 52.15?

  • A: In winter, the entire lake water is at a uniform 4°C, preventing stratification.
  • B: Spring turnover leads to thermal stratification due to surface warming.
  • C: During summer, a thermocline separates warm surface water from cold bottom water, leading to decreased oxygen at depth.
  • D: Autumn turnover primarily occurs due to surface water freezing, reestablishing the winter profile.

Explanation

Figure 52.15 and its caption clearly state that in summer, the lake regains a distinctive thermal profile with warm surface water separated from cold bottom water by a thermocline. During this period, the oxygen concentration decreases with depth due to lack of mixing.