A biologist subjects 200 plants to irradiation by X rays to induce mutations in the plants' genes. What should the biologist do to select for plants with mutations that knock out auxin production

by phenotypically identifying plants unable (or with an altered ability) to synthesize auxins. This approach is called reverse genetics

Explanation:

Reverse genetics is a strategy widely used in molecular genetics aimed at analyzing the function of target genes by identifying defective phenotypes of one or more organisms following the disruption of the gene. In this case, a mutagenesis approach (i.e., irradiation with X-rays) was used to induce mutations in the gene/s involved in auxin production. Subsequently, the resulting mutant phenotypes, i.e., plants with an altered ability to synthesize auxin, can be used to reveal the biological function of individual (mutated) gene sequences.