If 15% of the nitrogenous bases in a sample of dna from a particular organism is thymine, what percentage should be cytosine

So Adenine and Thymine are base pairs so they have to be equal to each other. So Adenine and Thymine are both 15% or 30% together.

This means there is still 70% left.

The next base pair is Cytosine and Guanine. they also have to equal to each other. Since there is 70% left you divide that number by two and you get 35%.

This means 35% is Cytosine in the strand of DNA

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.