Biology Questions

Here Homologous Means having the same relation or relative position or structure. 

Here in snakes poison is in glands and here salivary glands are in Vertebrates.

Eukaryotic cells all have a nucleus. Eukaryotes are organisms that are multicellular, although there are some examples of single cellular eukaryotes. So eukaryotic cells can be either cell with a nucleus or a eukaryotic organism's cell.

The most important feature to judge whether it has nucleus membrane.

And for other choices, they are the common features of eukaryote and prokaryote.

One reason the skeletal system is important is because the skeletal system creates the connective tissue and tendons that allow the body to move.