Question 117·200 Super-Hard SAT Reading Questions·Craft and Structure
Text 1
A bet-hedging model of seed dormancy distinguishes two responses to uncertain growing conditions. When reproductive success varies unpredictably among years and no early cue forecasts conditions, selection may favor germination of a relatively stable fraction of seeds each year, leaving the rest dormant. If an early signal reliably forecasts a favorable season, however, selection may favor cue-responsive germination. These strategies need not be exclusive: even a cue-responsive population may retain some viable seeds in dormancy. The model does not predict greater dormancy merely from low average rainfall.
Text 2
Ecologists studied two populations of the same annual plant. The populations' sites had nearly identical average rainfall and year-to-year rainfall variability. At the coastal site, however, unusually cool soil before the rainy season historically predicted wet winters; at the basin site, soil temperature had no such association. In a laboratory, researchers exposed otherwise identical groups of seeds to either a cool or a warm pulse before watering them. Among coastal seeds, 84 percent germinated after the cool pulse and 39 percent after the warm pulse. Among basin seeds, 46 percent germinated after the cool pulse and 44 percent after the warm pulse. Tests confirmed that comparable proportions of the ungerminated seeds from both populations remained viable.
Based on the texts, which choice best applies the model in Text 1 to account for the germination patterns in Text 2?
For cross-text questions, first state the principle or distinctions established in Text 1. Then map each important result in Text 2 onto that framework, paying attention to controls and qualifications. Prefer the answer that explains the complete pattern without overstating what either text establishes.
Hints
Distinguish the two strategies
Ask what pattern would indicate a stable partial-germination strategy and what pattern would indicate responsiveness to a forecast.
Compare treatments within each population
Focus on how much each population's germination rate changes between the cool and warm pulses.
Use the controls
Consider what the equal rainfall statistics and the viability tests rule out.
Step-by-step Explanation
Identify the model's two responses
Text 1 associates relatively stable partial germination with unpredictable conditions that lack a useful early cue. It associates changing germination rates with a signal that reliably forecasts favorable conditions.
Match each population to the model
Coastal germination rises from 39 percent after the warm pulse to 84 percent after the cool pulse, matching the historical value of cool soil as a forecast. Basin germination remains nearly unchanged because temperature has no predictive value there.
Account for the ungerminated seeds
The viability tests indicate that ungerminated seeds were dormant rather than dead. Thus, the coastal population can respond strongly to the cool cue while still preserving some seeds for future years, exactly as Text 1 allows.