Answer:
increasing extension time
Explanation:
The Polymerase Chain Reaction is a technique widely used in molecular biology laboratories to amplify target DNA regions. The standard steps of a PCR are as follow 1-denaturation, 2-annealing and 3-elongation/extension. These steps are repeated 15-40 times in order to exponentially amplify the linear DNA fragment. It is well known that longer extension times can be used as a strategy to increase the yield of longer PCR products. This is because the extension time depends on the synthesis rate of the DNA polymerase used in PCR technique and the length of the DNA fragment to be amplified.
The answer for this is A,
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.
