EK Biology 1001 Questions

[Ben25]

Can anyone explain this question......

Invertebrate ancestors of vertebreates did not have mouths, but used their gill slits for filter feeding instead of oxygen uptake. Oxygen was taken up instead through their skin. Which of the following animals is capable of oxygen uptake through the skin?

A. fish
B. Lamprey
C. frogs
D. Snakes

The answer is B, but I though frogs took alot of oxygen through their skin? Soln in the back of book discusses venous and arterial blood mixing, such animals are reptiles, amphibians, and animals that uptake oxygen their their skin. Its prob. 685 in the book.

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[Lbgem]

You're missing the point of the question. It's not basing it on what you may or may not know outside of the question, it's giving you info and asking you to analyze the answer based on what they give you.

You're looking for a species that 1. its or its ancestor had gills used for filtering and NOT oxygen 2. it or its ancestor had skin for oxygen uptake.

A. Fish is out - gills used for oxygen
C. Frogs - no gills, and its amphibian, possible answer I'll give you that
D. Snake - lives purely on land

I think any correct answer would have to have the species living in the water since oxygen is being filtered through the skin instead of the mouth, and that it feeds through its gills (last time I checked, nothing on land needed to do this). So the possible answers you're left with are:

B. Lampreys
C. Frogs

Now what's more likely - lampreys breathing through their skin because they live in the water 100% of the time, or frogs breathing through their skin living on land and water? Anyways, that's how I thought of it, may or may not be right.

 

[Isoprop]

+1 for Zoology majors!

The answer needs to have gills and not use it for respiration, but use it for filter feeding.

a) fish: has gills but purely for oxygen. also, eat and swallow.
b) lamprey: has gills. used for oxygen? maybe? how do lampreys feed? they stick their mouth onto another fish and suck on it for a long time. Oops, they can't use their mouths for breathing. Thus they have to breathe some other way.
c) frog: doesn't have gills. also, can swallow food
d) snake: doesn't have gills, definitely swallows food.

Also, the question stem indicates that this was a characteristic of invertebrate ancestors. Out of all three, lamprey is the most ancestral organism of the phylum Vertebrata.

 

[Charles_Carmichael]

I don't have my EK1001 book with me but I believe that the passage basically gives you the answer in the first paragraph; it basically tells you what all the wrong answers are.

 

[hyourinmaru]

I think while you could have inferred from the question what the answer was going to be, the question itself was poorly phrased. You are right, amphibians do use their skin for gas exchange.

However, the first sentence has said "invertebrate ancestor of vertebrates", which basically crossed out anything that's vertebrates: fish, amphibians and reptiles.

At least this is how I perceived it at a quick glance!