Second question please

Its bc plants can only take in so much nitrogen like compounds (nitrates, ammonium etc) to keep a stable ph level so ammonium is positively charged and nitrates are negatively charged they release hydrogen to equal the ph levels but since it’s already getting ammonium in the cycle it can’t receive more and the ratio must be compatible with the plants therefore not different.
Also, plants can’t take it in bc it needs the bacteria to break the ammonium down into a usable compound. Like nitrates.
I’m sorry if that was contradicting. I’m trying my best. :)

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.

There are four nitrogenous bases that make up dna. the two pyramidines are thymine and cytosine. the two purines are adenine and guanine. these bases pair in a very specific way. adenine - thymineguanine - cytosine i remember it like this: a tall, good cat.