Active transport, which occurs at the expense of energy.
Answer:
Active Transport
Explanation:
Active Transport is moving substances from lower concentration to a higher concentration.
The period during which the presence of stromatolites decline is the Proterzoic period. Stromatolites are widely distributed sedimentary structures consisting of laminated carbonate or silicate rocks, produced over geologic time by the trapping, binding, or the precipitating of sediment by groups of microorganisms, primarily cyanobacteria.
The geologic time scale is a system of chronological dating that relates geological strata to time, and is used by geologists, paleontologist, and other Earth scientists to describe the timing and relationships of events that have occurred during Earth's history. Hope I helped!
The only independent variable in this experiment is the amount of nitrogen Sarah uses. All of the other variables are dependent on other factor and processes, but Sarah controls the amount of nitrogen that she uses for each plant.
