In symbiotic relationships, two or more organisms always do which of these?

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.

it is called the mitotic spindle