PT.76.S4.Q25 - bird and reptile species hissing

rockytoral

This question went completely over my head and I still don't understand why the correct answer is (C) for all the tea in China. If someone could please explain this question it would be greatly appreciated!

Perhaps some insight to these questions in general. These use to be my best question types until I hit PTs in the 70s...

Thanks!

kennedybj

IS this the one about birds and reptiles?

kennedybj

So the stem says many birds and reptiles use hissing as a threat device against predators. Then it says that the hissing sound between reptiles and birds is similar, so it is likely that the hissing developed from a common ancestor. However, it then tells us that none of the common ancestor's predators at this time could hear the hissing. So based just on that we know that hissing sound is not what threatened predators so there must be something else that the hissing does to scare away predators that isn't a noise. Answer C states that by producing a hissing sound, it would have increased the body size of the common ancestor. Bingo. The larger body size scared off the predators, not the hissing noise itself since the predators couldn't hear.

c.janson35

I think it's useful to phrase these questions in terms of "why/how...... even though....?" For example, this question would read: "how is it that hisssing developed from a common ancestor to fend off predators even though the common ancestor's predators could not have heard the hissing sound?" The right answer will always answer this question. We are looking for a reason that this could be so, which means you are allowed to expand the scope of your answer to include some information that would be helpful in answering (this is why there is an "if true" in the question stem).

You may not be able to prephrase the exact answer here, but that's not necessary to answer the question. What is important is that you key in on how to answer the above question. Here, we need some way that hissing could warn off predators that could not hear. Maybe the hissing is accompanied by a rise in body temperature that can be perceived by predators and is interpreted as a threat. Maybe the hissing was initially accompanied by some sort of venomous spit that scared predators away. Or maybe the hissing was accompanied by an apparent change in body size which makes the bird/reptile more threatening to their predators, as C says. You have to be flexible enough with your understanding to be able to see C and say, "yes this could be an answer to initial question; this answer indicates that hissing was not always just an auditory threat, but also a visual threat as well."


Hope this helps!

kennedybj

Answer choice A just tells us that the common ancestor of birds and reptiles couldn't hear the hissing sound either. That doesn't explain anything.

kennedybj

Answer choice B says the common ancestor probably had multiple threat devices. Okay, that still doesn't explain why they hissed when predators couldn't even hear the hissing.

kennedybj

Answer Choice D says hissing would have been less energetically costly. But what does it matter if its less costly if the predator cant hear it? might as well just lay there and play dead lol

kennedybj

Answer choice E says the common ancestor would have had few predators. So What? Having few predators caused them to develop hissing even though their few predators couldn't hear the hissing? Doesn't explain why hissing was developed if the predators couldn't hear them. Imagine a tennis with few competitors developing a nice basketball jump shot just because he has few competitors. lol