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.

The correct answer is option d. "Serratia genes for pigment production are induced at certain temperatures".

Explanation:

In this study, a gene of the bacteria Serratia marcescens is being tested, and the results shows that at 25 Celsius the agar plate of the bacteria is red while  at 37 Celsius is nonpigmented. With this initial results it is certain to conclude that Serratia genes for pigment production are induced at certain temperatures. However, the nature of the genes regulation is yet to be elucidated, further studies must be performed to make conclusions.

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.