What was c? But I think its A.) a molecule that changes state.
Respiration using oxygen to break down food molecules is called aerobic respiration. 'Aero' means air, which contains oxygen, leading to the name aerobic respiration. Glucose is the molecule normally used for respiration - it is the main respiratory substrate. Glucose is oxidised to release its energy, which is then stored in ATP molecules.
The word equation for aerobic respiration is:
glucose + oxygen → carbon dioxide + water (+ ATP made)
You need to be able to recognise the chemical formulas:
C6H12O6 + 6O2 → 6CO2 + 6H2O
The shape that would be the most desirable for cells would be the Cylinder shape.
Wouldn't it be water vapor? Don't quote me on this, but I think when water Molecules (H2O) heat up, they expand away from each other and become gas.