In gravitropism, in which direction do roots grow?

Roots will always grow down due to geotropism. It is caused by the statocytes in the root cap. They sense the force of gravity and grow down according to it. But if the root does not have a root cap, then the plant will not necesarily grow down. And if the seed is layed on a flat place like a counter, then the roots will grow any which-way

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.