Which one of the following choices is not one of the main processes that allow nutrients to be absorbed from the gi tract into circulation?
a. passive diffusion
b. active diffusion
c. facilitated diffusion
d. active transport

The choice that doesn't reflect a main process which allows nutrients to be absorbed from the GI tract into circulation is active diffusion among these possible answers. So your answer would be B - active difusion.

The main reason for this is that all of the other ones are implicated and play active roles in the process of nutrient absorption from the GI tract into circulation. 

Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.

1) clean up you lab area2) dispose of the chemicals as instructed by your teacher3) put everything back where it belongs unless your teacher tells you otherwise4) dispose of gloves5) wash hands with soap and water