Which must an animal do in order for cellular respiration to begin?

Answer is: eat food.

Chemical reaction of cellular respiration (convert biochemical energy):

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O.

glucose + oxygen → carbon dioxide + water + energy .

This reaction is exothermic (energy is released).

Carbon dioxide and water are released during cellular respiration.

There are 18 oxygen atoms (six in glucose and twelve in six molecules of oxygen) in left side of chemical reaction and also 18 oxygen atoms (twelve in six molecules of carbon dioxide and six in six molecules of water) at the right.

answer is: naturally occurring solid, inorganic compound or element is mineral.

minerals usually have crystalline form, that means than crystal constituents (atoms, molecules or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

for example magnetite is a mineral of iron oxide (fe₂o₃).

calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (caco₃).

dolomite is an   carbonate mineral composed of calcium magnesium carbonate (camg(co₃)₂).

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.