Can the number of chromosomes per cell be doubled? plz answer asap

Some birds look for food near cattle and other livestock. the movement of the cattle churns up the ground, making insects available to the birds. the cattle appear to be unaffected by the presence of the birds. what kind of relationship exists between the birds and the cattle? o a. parasitism o b. commensalism o c. predation o d. mutualism

Iwanna go do something with my ideas? ?

What substance acts to prevent sudden ph changes in bodily fluids?