#13 - Unlike other primroses, self-pollinating primroses do

[nusheenaparvizi]

Hi,

Q13 from June 1998 LR2 asks to resolve the apparent discrepancy, but when I was reading this problem I could not find any discrepancy in the stimulus? I did find the 2 middle sentences of the stimulus odd:

"In many years insect pollinators are scarce, and in those years a typical non-self-pollinating primrose produces fewer seeds than does a typical self-pollinating primrose. In other years, seed production is approximately equal."

I thought maybe the discrepancy lied in how/what made the seed production to be approximately equal, but none of the answer choices seemed to reflect my prephrase. Answer choice B makes no sense to me at all and I do not understand how insects being scarce and non-self pollinating primroses producing larger seeds would resolve the discrepancy I've noted above, or any discrepancy in the stimulus for that matter.

Thank you so much for your help!

Nusheena

[Adam Tyson]

The paradox here, Nusheena, is that self-pollinating primroses produce more seeds, on average, but are more rare than the others. We need an answer that helps to explain why they are more rare, rather than being more common. After all, if they are putting out more seeds, shouldn't there be more of them than of the other kind?

The answer will be something that either tells us a problem with the self-pollinators (maybe their seeds are weak and puny and don't grow much?) or an advantage of the non-self-pollinators (they have super seeds that grow more, perhaps?) Answer B does the latter by showing us that the non-self-pollinating primroses produce larger, better seeds when times are tough, perhaps more than making up for their lower seed production numbers. Not just larger seeds, but seeds that are more likely to germinate! Thus, they are more likely to grow into new plants, outnumbering the self-pollinating primroses.

I hope that helps resolve the discrepancy for you!