A student prepares a cell homogenate from spinach leaves. She performs a cell fractionation experiment to determine the centrifugal force (g-force) that will yield the highest percentage of chloroplasts in the pellet fraction. She splits the spinach homogenate into 5 equal parts and centrifuges the parts for 10 min. at 500xg, 1000xg, 1500xg, 2000xg, or 2500xg. She then determines the proportion of chloroplasts in the supernatant and pellet fractions. The dependent variable in the student's experiment is:

the proportion/percentage of chloroplasts in the supernatant and pellet fractions

Explanation:

The dependent variable of an experiment is the variable that is measured by an experimenter or the variable that responds to changes made to another variable (independent variable). The dependent variable is dependent on the independent variable.

In this experiment, a student performs a cell fractionation experiment in order to determine the centrifugal force (g-force) that will yield the highest percentage of chloroplasts in the pellet fraction. The centrifugal force is the independent/manipulable variable while the DEPENDENT VARIABLE IS THE PROPORTION/PERCENTAGE of CHLOROPLASTS in the SUPERNATANT and PELLET FRACTIONS.

they may bind directly to special “promoter” regions of dna, which lie upstream of the coding region in a gene, or directly to the rna polymerase molecule.