Aamc 9 bs #96

[curt656]

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This question is for anyone who has access to AAMC 9. This question just flat out pisses me off. Forgive me if you don't have access as this question is passage based and I am not going to type the whole damn thing out.

I cannot for the life of me figure out why the answer is not A based on the "degenerative state...[where] a previously existing vascular connection was lost."

Apparently the answer is B: "Ancient agnathan axes are similar to existing bird axes." HOW IN THE F IS THIS THE ANSWER??? If a previous fossil had the connection and the modern ones don't, isn't that the very definition of the degenerative state hypothesis? And where in the hell is there a connection in the passage between "Agnatha (the jawless fishes)" and birds other than that they are both vertebrates. Well hell, if all living vertebrates have the vascular connection and agnathans are the only vertebrates that do not, I can draw a similar connection to ANY existing vertebrate based on the fossil evidence.

I apologize for asking you to look this up, but if anybody would and can explain to me why B is the answer, I will buy you several beers if ever we meet.

 

[V5RED]

This question is for anyone who has access to AAMC 9. This question just flat out pisses me off. Forgive me if you don't have access as this question is passage based and I am not going to type the whole damn thing out.

I cannot for the life of me figure out why the answer is not A based on the "degenerative state...[where] a previously existing vascular connection was lost."

Apparently the answer is B: "Ancient agnathan axes are similar to existing bird axes." HOW IN THE F IS THIS THE ANSWER??? If a previous fossil had the connection and the modern ones don't, isn't that the very definition of the degenerative state hypothesis? And where in the hell is there a connection in the passage between "Agnatha (the jawless fishes)" and birds other than that they are both vertebrates. Well hell, if all living vertebrates have the vascular connection and agnathans are the only vertebrates that do not, I can draw a similar connection to ANY existing vertebrate based on the fossil evidence.

I apologize for asking you to look this up, but if anybody would and can explain to me why B is the answer, I will buy you several beers if ever we meet.

The question asks you to imagine that the ancient agnathans had a trait that modern birds have and then draw a conclusion from it.

"A" is ruled out because it makes no sense. A degenerative trait means they had something and lost it. We have no information about even older agnathans having more advanced axes that degenerated to ones similar to bird axes, and even if we did it would have nothing to do with the question.

"B" makes perfect sense because it is just a rewording of the information in the question paired with some passage information in a very logical way.

 

[curt656]

The question asks you to imagine that the ancient agnathans had a trait that modern birds have and then draw a conclusion from it.

"A" is ruled out because it makes no sense. A degenerative trait means they had something and lost it. We have no information about even older agnathans having more advanced axes that degenerated to ones similar to bird axes, and even if we did it would have nothing to do with the question.

"B" makes perfect sense because it is just a rewording of the information in the question paired with some passage information in a very logical way.

But the question, or the passage for that matter, says nothing about birds whatsoever. The question states that the fossil shows that they had the trait and now they don't. To me the fossil is proving the degenerative hypothesis!?!?!?! I am so confused. I guess the wording is too ambiguous for me. That or I am ******ed, lol. Thank you for your reply.

Edit - If we ever meet, I will buy you several beers!

 

[V5RED]

But the question, or the passage for that matter, says nothing about birds whatsoever. The question states that the fossil shows that they had the trait and now they don't. To me the fossil is proving the degenerative hypothesis!?!?!?! I am so confused. I guess the wording is too ambiguous for me. That or I am ******ed, lol. Thank you for your reply.

Edit - If we ever meet, I will buy you several beers!

I will try to explain better.

The passage states that all living vertebrates have a vessel connecting the hypothalamus and the pituitary. Birds are vertebrates, so it can be inferred that they have such a system.

If the ancient agnathans had such a system, as supposed in the question, then it would mean they are similar to birds.

The degenerative hypothesis states that modern agnathans are a degeneration from agnathans that had the aforementioned system. If true, the information in the question would support the degenerative hypothesis, but answer "A" does not actually talk about the degenerative hypothesis.

Answer A says that the ancient agnathan system is degenerate which would mean that its ancestor(ie the ancestor of the ancient agnathan) had evolved the system and then lost it. Answer A says nothing about modern agnathans. The part that I think is confusing you is that they use the word degenerate, and the information in the question would support the degenerative hypothesis, so you are associating "A" with the degenerative hypothesis when it actually is unrelated.

This confusion does not mean you are stupid, it just means that the AAMC was successful in their attempt to confuse you by using wording that could drive you to make a connection that isn't there.

 

[AnnJ716]

I had a problem with this one as well. With this type of question, would it be best to think about each answer and then eliminate?

 

[Trayshawn]

POE is definitely the best for these kinds of questions.
The passage doesn't mention birds explicitly, you're right about that. So I would've just skipped that answer and move on to see if any other ones made sense. None of them do.
Thats when you go back to the bird answer choice and see if you can make sense of it.
The passage mentions that all vertebrates have the hypo/pit axis. Birds are vertebrates.
If the ancient agnathans had this axis as well, then they are similar to birds.