a) digestive system - Which came first food, appetite, ability to eat, digestion, resistance to one's own stomache acid.
Well, let's look at each of these.
Food - This is kind of broad. Just about everything can be (and is) food for something else. So, food would have existed before anything was actually eating it.
Appetite - I have no idea how you would determine if, say a bacteria, has an appetite as we think of it. Seems reasonable that it would have some indicator that it needs to consume. But, seems just as reasonable that it simply consumes anything which is available as it comes across it.
Ability to eat - Yeast is a fairly simple organism. It "eats" starches, but it doesn't have a stomache as we would normally think of one.
As for digestive juices and our resistance to them, I would think that these kind of go hand in hand. The first thing to develop stomache acid that eats itself probably didn't last long enough to pass it on.
b) Drive to reproduce / ability to reproduce
Ability to reproduce is observable in even the simpliest of single cell organisms. And, like appetite, I don't know how we would determine if these things have a "drive" to reproduce.
c) Lungs / mucus / throat / mixture of gases
Well, gases of course came first, since that's the atmosphere. If our atmosphere had a different make up, then respiration would have to make use of whatever's there.
The throat predates lungs and mucus as well, as the throat is part of the digistive system and it observable in many different sea creatures who have no respiratory function whatsoever.
As for the mucus lining vs the lungs, that's a toss up. You could argue that certain fish (and other animals) have the ability to fill air bladers which don't serve as part of respiration. Are these primative lungs? You could also suggest that the mucus that lines the lungs is similar to that which lines the gills.
d) DNA or RNA
Well, RNA is ribonuclaic Acid and DNA is dioxy-ribonuclaic acid. So, I'm pretty sure that RNA is the building block on which DNA expanded.
e) Termite vs stomache flagella
I'd say the flagella existed (in one form or another outside the terminte) first. I think that the insects that we see as termites today, may have been more like ants until the flagella took up residence. Then, co-evolution kicks in.
Flagella evolves to be better at digesting cellulose, better at living in termites rather than out in the open, etc. Termites evolve to be better at obtaining cellulose to feed the flagella.
f) Bees vs Plants
I think NWR posted a great explaination of this above. Primative plants, like ferns, reproduce with spores instead of seeds and therefore don't need pollination. They predate the flowering plants.
In fact, the flowering plant "explosion" coincides nicely with the "insect explosion" as both groups rapidly diversified and conquered. (Please note that "rapidly" in geological/evolutionary terms can mean millions of years).
g) Immune system or need for it
Well, the need arose first. After all, the need for an immune system kicks off as soon as we have something alive which is threatened.
I suppose what you are asking is about viruses and such. Our immune system reacts to non-living intruders (ie splinters). But, I couldn't tell you the first thing about the first immune systems to evolve.
Do bacteria have immune systems? Does mold?
These are great questions. Hopefully someone can answer them for both of us
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