PT155 S2 Q3 ExplanationBiologist: DNA analysis show

Answer choices, explained

1. A

   Weakens, if anything1% picked this

   A. koa branches carrying seeds can remain afloat for prolonged periods

   We would either say this does nothing to add plausibility to the seabird hypothesis, or we might even say that this strengthens the Alternate Hypothesis that the seeds could have potentially floated from Hawaii to Reunion. The author rejected it on the basis that, "If the seeds got wet, they wouldn't be able to grow on Reunion", but this answer is making it sound like maybe the seeds could make it there without getting wet? Maybe the tree branch could stay afloat long enough that some of the seeds would stay dry?

   1%
2. B

   Correct97% picked this

   There are mountain-nesting seabird species common to Réunion

   Why this is right

   This adds plausibility to the seabird hypothesis by telling us that there are bird species who live in both Reunion and Hawaii (thus, there might be a migratory pathway that seabirds take from one place to the other). When this biologist first says her hypothesis, "Maybe seabirds took the seeds from Hawaii to Reunion?", we can imagine a skeptic saying, "Bah! Are there even birds that can make that trip? Do seabirds ever fly from Hawaii to Reunion?" This answer is providing a clue that makes it sound like maybe there are seabird species making the trek back and forth.

   Skill tested: Strengthen · how this choice captures the argument's function is the move to repeat next time.

   97%
3. C

   No Impact1% picked this

   A. koa is thought to be descended from Acacia melanoxylon, a tree native

   This does nothing to increase the plausibility of the hypothesis that seabirds took seeds of A. koa from Hawaii to Reunion. This is just telling us an origin story for A. koa, which doesn't have any bearing on our conversation.

   1%
4. D

   Weakens, if anything0% picked this

   Ocean currents have sometimes carried buoyant objects from Hawaii

   This answer seems to support the Alternate Hypothesis that seeds floated from Hawaii to Reunion, because it's establishing the possibility of something floating from Hawaii to Reunion. This doesn't do anything to make us think that seabirds carried the seeds from Hawaii to Reunion.

   0%
5. E

   Weakens, if anything1% picked this

   Many seabird species return to land very infrequently, and often do so

   This seems to somewhat hurt the hypothesis that seabirds took seeds from Hawaii to Reunion, because that would be a land-to-land trip, and this answer is saying that many seabird species very rarely return to land.

   1%