Serratia marcescens bacteria has a gene that regulates red pigment production by cells. a student inoculates two nutrient agar plates of serratia and incubates one at 25oc and the other at 37oc. following incubation, the student observes that colonies on the 25oc plate are red while those on the 37oc plate are nonpigmented. which of the following statements is a logical conclusion based on these results? a. low temperatures cause repression of certain housekeeping genes.
b. serratia cells undergo a genotypic change that is proportional to changes in temperature.
c. this is an example of constitutive gene expression.
d. serratia genes for pigment production are induced at certain temperatures.