Q21

[jennifer]

Can someone explain why the answer choices are correct for question 21...thank you

[noah]

I'd do that, but I don't think I'd be doing you a service. Let's start with the passage. What do you think the two sides of the scale are for this passage? It's a tough one!

If you have trouble with that, instead of telling me the scale, try writing out the main point of each paragraph.

I look forward to seeing what you think...

[jennifer]

I am not sure if there is a scale, it seems more like an informative passage. If I had to make a scale it would be Embryo's that establish polarity prior to fertilzation vs. embroyo's that establish polarity after fertilzation.
Before>fruit fly
After>nematodes, worms, frogs

Main Point is Line 53-57.

I reread it, and have narrowed down my questions to #21, thank you for your help.

[noah]

Sorry about the blank post - we had some tech issues yesterday.

I think you're right that there is not a scale in the sense of an argument between two sides, but I think there is a scale in a sense of comparing two things. I'd say it's

mechanisms for later embryonic development is similar among various species
vs.
mechanisms for early embryonic development to establish polarity varies among species

As for Q21, this is an inference question, so we're looking for something that is a slight step off the passage. (C) is inferrable from lines 42 - 44. If a question is tempting, we can assume that the author would agree that scientists will try to answer the question.

(A) is unsupported - while there is some discussion of the relative speed of embryonic development, there's no comparison between simpler and more complex organisms (is a nematode more or less complex than a fruit fly?). This is tricky because we learn about simple vertebrates, but that's not where we learn about the speed of development.

(B) is unsupported. We don't know for how many organisms scientists have worked this out.

(D) is tempting - we do learn that there is a lot of variety, but perhaps that variety can be categorized into groups.

(E) is similar to (A).

Does that clear it up?

[noah]

Sorry about the blank post - we had some tech issues yesterday. And bravo for figuring out the other questions - I figured that a close re-read would do that. That's half of the point of reading for the scale; that sort of read forces a more active read.

I think you're right that there is not a scale in the sense of an argument between two sides, but I think there is a scale in a sense of comparing two things. I'd say it's

mechanisms for later embryonic development is similar among various species
vs.
mechanisms for early embryonic development to establish polarity varies among species

As for Q21, this is an inference question, so we're looking for something that is a slight step off the passage. (C) is inferrable from lines 42 - 44. If a question is tempting, we can assume that the author would agree that scientists will try to answer the question.

(A) is unsupported - while there is some discussion of the relative speed of embryonic development, there's no comparison between simpler and more complex organisms (is a nematode more or less complex than a fruit fly?). This is tricky because we learn about simple vertebrates, but that's not where we learn about the speed of development.

(B) is unsupported. We don't know for how many organisms scientists have worked this out.

(D) is tempting - we do learn that there is a lot of variety, but perhaps that variety can be categorized into groups.

(E) is similar to (A).

Does that clear it up?

[ttunden]

so I guess that on these global inference questions we are suppose to work wrong to right?

I don't see how I could ever prephase C.

I would have to hunt that down in the passage because I wouldn't remember something like that from the 2nd paragraph, just the different ways polarity can be established in nematode,fruit fly, humans, simple vertebrates, and so forth. As well as remembering the p-granules and various traits about fruit fly/nematode/humans.

[tommywallach]

Hey Ttunden,

Yeah, pre-phrasing is great when it works, but particularly on general Qs like this, it's almost impossible to figure out where they're going to go. "Wrong-to-right" should be the go-to method overall; pre-phrasing is a great shortcut when it's available.

-t

[LaurenC742]

I still don't understand why (D) is the wrong answer. "Very few observations of embryonic development after polarity is established are generalizable to more than a single species." This statement seems consistent with the conclusion drawn in the last paragraph. The phase of embryo established polarity is radically different from each species whereas the developmental mechanism after deciding polarity is remarkably similar among species.

Any clarification? Thank you!