The most specific would be felis catus. That is the name of the species in biology, and there are no more taxonomic divides after species.
Perception of pitch and sound intensity is the cocklear
The difference between the two students that we know of is that they used a different meter stick. So the difference would be best attributed to the different tools they used.
Note, this is quite a huge difference. It's likely that one of the sticks, or both, are quite defect.
The aorta, which arises directly from the heart