Biology HL
Climate Feedbacks and Ecological Timing
- 1.
Explain how warming that reduces sea-ice cover can amplify further warming through an albedo feedback. Distinguish this feedback from the initial anthropogenic increase in greenhouse gases and from a stabilizing negative feedback.
[4 marks] · no calculator - 2.
In a hypothetical forest, peak caterpillar abundance shifts from day 140 to day 128, but peak nestling food demand shifts from day 142 to day 138. Calculate the gap between the two peaks before and after the shift, and explain a possible consequence for birds whose young depend heavily on caterpillars. Suggest why the two populations might respond differently to changing seasonal conditions and state one limitation of predicting bird population change from peak dates alone.
[4 marks] · no calculator - 3.
Compare how increased seawater temperature and increased dissolved carbon dioxide can threaten a coral reef. Distinguish bleaching from reduced calcification and explain one food-web consequence if living coral cover declines.
[4 marks] · no calculator - 4.
In a hypothetical region, snow and ice retreat, exposing darker land. Explain the ice-albedo feedback and distinguish a positive feedback from the claim that every region must warm at the same rate.
[3 marks] · no calculator - 5.
Initially, a hypothetical caterpillar food peak coincides with peak food demand from an insect-eating bird's chicks. Over a decade, the food peak moves ten days earlier but peak chick demand moves only two days earlier. Explain the new timing mismatch and propose a measurement needed before concluding that this change caused lower breeding success.
[3 marks] · no calculator