Embryo Polarity

Answer choices

1. A

   Out of Scope: articulate a theory5% picked this

   articulate a theory of how early polarity is established and support the theory by an

   There's no unitary theory of how early polarity is established. The passage is emphasizing that there are lots of different ways that early polarity is established.

   5%
2. B

   Correct69% picked this

   describe a phase in the development of organisms in which the genetic mechanisms used are disparate and discuss

   Why this is right

   "Establishing polarity" is a phase in the development of organisms, so, yes, the passage describes the phase where organisms establish polarity. Does the passage say that the genetic mechanisms are disparate? Yes, this is half of the paradox we were looking for. As the final paragraph says, "the mechanisms of development used [to establish polarity] are vastly different". Does the author discuss why this disparity is surprising? Yes, she calls it a "seeming paradox". Paradoxes are inherently surprising. It's surprising that organisms vary so much in terms of how they establish polarity, because once they've established polarity, "there is an astonishing conservation of mechanism --- the developmental mechanisms used are remarkably similar" when it comes to building eyes and ears and spinal cords and such.

   Skill tested: Primary Purpose · how this choice captures the passage's function is the move to repeat next time.

   69%
3. C

   Out of Scope: a classification15% picked this

   provide a classification of the mechanisms by which different life forms

   The author definitely discusses several mechanisms by which different life forms establish early polarity. But does she provide a classification? Does she say, "birds use p-granules, amphibians use a pre-polarized egg, mammals use X, etc.?" No, there are just a handful of one-off examples. We know how the fruit fly establishes polarity and how certain nematodes establish polarity. She then says that some simple vertebrates might do something similar, but no one really knows what more complex vertebrates like mammals do. So it's hard to say that there's any classification system provided. This answer also would do a worse job than the correct answer does of describing what happens in the final paragraph.

   15%
4. D

   Too Strong: must occur in all8% picked this

   argue that a certain genetic process must occur in all life forms, regardless of

   The author never says anything super-extreme like "there is a genetic process that must occur in all life forms". We could potentially say that the first sentence identifies "establishing polarity" as something that must occur in all life forms for an embryo to develop". But the author isn't arguing that must occur. She just states that it does occur and then starts talking about different ways that it occurs.

   8%
5. E

   Out of Scope: explain why3% picked this

   explain why an embryo must establish early polarity before it can develop

   The author never explains why an embryo must establish early polarity. It's just sort of common sense that you can't build a building if you don't know which direction is up and which direction is down. Similarly, DNA can't build an organism if it doesn't have an initial sense of top vs. bottom. The author never explains this, and it's certainly not what the bulk of the passage is doing.

   3%