Amicrobiologist is working with two genera of bacteria, a and b, to determine if cells are competent. strains are grown under optimal conditions, and dna fragments that carry the gene for green fluorescent protein is added to each culture at 20-minute intervals. samples from each treatment are plated to nutrient agar and incubated, after which the plates are examined under an ultraviolet lamp. the microbiologist observes that all plates of bacteria b contain colonies that are fluorescent, while for bacteria a only the plates from stationary phase demonstrate fluorescent colonies. what can be concluded from these results?