I think its the second choice
A cell is the building block of an organism, or the smallest unit of life. The creatures inside provide food and energy to us, because we can't make our own energy.
i know that this is late, but for future kids
the answer is nucleic acids
Water displacement, after all, the water that's displaced is used to calculate the volume of the irregular shaped object. Hope my answer helped!
Oxygen is needed by aerobic organisms for cellular respiration process. Oxygen happens when the muscles are working faster than energy can be produced. Energy is still produced but anaerobic process is done to cope up. The signs of oxygen debt are panting and muscle fatigue.
