Because they have volicules
Some of the advantages of this is you get to have more control of the event that transpire as well as being able to study and observe said events closer. a Disadvantage would be that you're not able to the real thing as in what would actually happen naturally for example if you set up an aquarium it may have a negative affect on the fish or the fish may act a different way in the smaller space as it wouldn't be used to it.
Hope this help! :)
Answer:
It is possible for two of the same species to have differences in their DNA.
The control group is the one that won't receive fertilizer.
