from ek:

all of the following are characteristics of members of the phylum chordata at some point in their life cycle except:

1)tail
2)notochord
3)backbone
4)gills.


apparently, the answer is (3) or backbone, because "backbone" is part of the subphylum vertibrata. Doesnt that mean it is automatically part of Chordata?

its driving me crazy!! please help

no because while all vertibrata are chordata not all chordata are vertibrata. If having a backbone was a characteristic of chordata then ALL chordata would need to have a backbone.

i didn't even study this kind of stuff for the mcat.

Chordata have these characteristics : post-anal tail, pharyngeal gill slits, notochord, and a dorsal hollow nerve cord. That's what I remember from zoology. Wikipedia says there is a 5th called an endostyle but I had never learned that one.

backbone is wrong cause not all chordates have them. Tunicates (sea squirts) are a perfect example.

Yeah I am pretty much ignoring taxonomy.

I'm not sure what all I'm allowed to say but this topic was on the Jan 25 test.

As stated earlier it is kind of a trick question. The notochord is really the chordata. A backbone is a fairly complex evolutionary feature compared to the others. Endostyle is another feature, but one can ignore that. It isn't too important. Sea squirts are kind of an odd little thing in that some of the stuff they have at the beginning and it kind of just fades away resulting in something that looks anything but a chordata.