Narrator: Listen to part of a lecture in a biology class. Professor: Today we're going to talk about a fascinating adaptation in desert plants: the phenomenon of 'seed dormancy.' Some seeds, like those of the desert annual plant *Boechera*, can remain dormant in the soil for years, waiting for the right conditions to germinate. What triggers germination? Well, it's not just water. In many deserts, a single rainstorm can occur at any time of year, but if seeds germinated after every rain, they'd be killed by the subsequent drought. So, these seeds have evolved to require a specific cue: a series of light rains that leach inhibitory chemicals from the seed coat, followed by a period of cooler temperatures. Only after this sequence do they germinate. This ensures that germination happens during the brief, reliable wet season when the chance of survival is highest. Interestingly, not all seeds in a single plant's seed bank germinate at the same time. This 'bet-hedging' strategy means some seeds stay dormant even when conditions are perfect, ensuring that at least some survive if the season turns out to be unusually short. So, seed dormancy is not just a passive state; it's an active, finely tuned survival mechanism.
❓ 题目 According to the professor, why do desert seeds like those of *Boechera* require a specific sequence of rain and temperature changes before germinating?
A. To ensure that germination occurs only when water is plentiful, regardless of temperature.
B. To prevent germination after isolated rains that would not support seedling survival.
C. To allow all seeds in the seed bank to germinate simultaneously for better growth.
D. To respond to any rainfall as long as the soil is moist enough.
✅ 正确答案
To prevent germination after isolated rains that would not support seedling survival.