Exactly how realistic is it to use anything as a bioweapon?

Yes, it's possible, if you have the right kind of technology. At this time, humans are still in the stone age compared with the Engineers.

One phase they are alien... so it is impossible to know the details of their genealogy... its all fantasy anyway so its the writters rules...

Thank God for The CDC! The doctors and research scientists there are constantly looking for this type of threat (remember Anthrax?) Unfortunately, bio-weapons are real which makes we Humans look pretty damned bad.

Another word Smallpox!

Oh, and plain simple alcoho!l Harmless on its own, but mix it with certain mammals... and its Organic in origin with the simplein take-in system of addiction!

The engineers would have no problem using bio weapons on planets. They would just drop them from space. Even safer than chemical warfare here on Earth. The problem, apparently, according to the movie, there is a slight danger in preparing the weapon. Then again, everything on Earth would be dead if the "accident " hadn't happened and there would be no movie.

Yea but is that even possible both in biology and in physics that something could grow that fast within hours? Has nothing to do with the CDC...

bear in mind most of our technology is biologically fueled (oil) biology is renewable, also uses the power of exponential growth

mechanical weapons are simpler and cheaper, but their effect is massive and without target differentiation. with A bomb you kill all. with well designed bioweapon based on DNA, you can target only those you want.

Simple and depends on using a Organism thats higher on the food chain. If you had a Rat Infestation at a Warehouse you could take in a few cats and keep them there, and they would in effect be your Bio-Weapon against the Rat Infestation. If you could give Big Cats like Lions and Tigers the killer instinct and food chain mentality towards humans that Dogs or Bears have then you could turn a Lion into a Weapon that would hunt Humans as Prey. At the moment apart from insects and parasites the only Animals that actively would see Humans as Prey are Bears and Dogs. If mankind was to create a Bio Weapon Organism, i would think that some kind of Insect, Rodent or Bird would be used for the purpose of spreading a contagion