Place the following events of muscle contraction in the correct order. t 1. Cross bridges form
2. Signal travels down the motor neuron
3. Calcium released from sarcoplasm
4. ATP creates a power stroke, shortening actin filament
5. Actin changes shape

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.

Well,what i learned was that unlike many other  endothermic  reactions,  photosynthesis  does not absorb energy as heat. instead, during plants absorb energy from sunlight to turn carbon dioxide and water into oxygen and glucose, which is a type of sugar molecule. the energy is stored in the glucose molecules, ready to be used when needed.