Answer:
B) All DNA molecules will migrate up the gel toward the positive electrode.
Explanation:
Because the DNA has a negative charge - regardless the size-, all DNA molecules will migrate towards the positive electrode, at the top of the gel. This is due to the Coulomb's physic law "force of the interaction between the charges is attractive if the charges have opposite signs".
Instead of migrate down the gel , the DNA will do migrate up the gel (opposite direction).
Oxygen.
Oxygen was fatal when organisms started using photosynthesis, this event was known as the Great Oxidation Event.
They are surrounded by the sepals. :)
