You have isolated two different yeast strains, strain 1 and strain 2, each of which fails to grow in the absence of arginine. You want to clone the wild type copy of the gene or genes that are mutated in strain 1 and strain 2. To do so you plan to:

the answer is:

carbon dioxide

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.