What are the main functions of meiosis

To create sex cells that are ready for reproduction ex: sperm and egg cell

The main function of meiosis is to produce gametes (e.g. egg/sperm cells). These are cells with half the number of chromosomes that are in a normal body cells. It is also to produce variation because during meiosis genes are switched round in homologous chromosomes (this is called crossing over) and the homologous chromosomes are independently assorted, which means different random mixtures of chromosomes end up in the gamete cells produced each time meiosis happens.

Hmmm i'm not sure about this one

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.