What characteristic do all members of eukarya have that members of eubacteria do not have?

The best answer would be:

A membrane bound nucleus

Here is more about the question:

There are three domains in the classification of organisms and they are Eubacteria, Archaea, and Eukarya. What makes Eukarya different from the other two is the presence of a nucleus in the cells. Among the remaining two, Archaea is more closely related to Eukarya than Eubacteria.  

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.

the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.