The purpose of adding blue "tracking" dye to the DNA samples is to make it easier to visually track the DNA migration to the positive pole in the electrophoresis chamber. TRUE FALSE

True.

Explanation:

DNA molecule is negatively charged and can move towards the positive pole the electrode. DNA electrophoresis is a technique used for the separation of DNA molecules on the basis of their size.

The small fragments move faster than the large fragments on the gel. The blue bromophenol dye also known as tracking dye is used for the visualization of DNA molecule and their migration on the agarose gel. The tracking dye is used to lade the samples easily as well.

Thus, the answer is true.

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.