User blog comment:Mabr/Vampire anatomy/@comment-3201389-20100329170916

In order for them to bleed (for any reason) their heart would have to be pumping, which it's not.

I don't remember any mention of Bella's hair growing longer when she changes, if it's in there - you need to site where. Growth aside, when they cut their hair, I would expect it to "heal" by growing back to the same length it was when they first changed.

Also, this is fantasy, not reality, so trying to match it up with scientific fact is a fruitless endeavor. The chromosome issue in this series is a perfect example of that.

Another example of a "scientific" error is in Jacob's imprinting on Renesmee. The imprinting process is supposed to be a way for the imprinter to find their ideal genetic match, allegedly for the purpose of reproduction. Right off the bat, Renesmee is a hybrid of two different species, which in nature, leads almost always to infertility. (the mule for instance) Then she would be trying to mate with a creature of yet another distinctly different species. If that isn't enough, when Renesmee reaches the age of 16-17 (pretty much barely old enough to bear children) she stops aging and takes on her father's immortality characteristics. This would include the same inability to change physically that prevents Rosalie from bearing children.