When the size of opening of the iris diaphragm is reduced

Q1. 1) Why is agar preferable to gelatin as a solidifying agent in culture media?

2) Did all the organisms living in or on the environments sampled grow on your nutrient agar? In brief explain.

3) How might you find out whether the turbidity in your nutrient broth tube was from a mixture of different microbes or from the growth of only one kind of microbe?”