Answer:
Alternative splicing explains how it works
Explanation:
Two different transcripts can be produced from one single gene according to the nature of exons and introns of every transcript, which means that a group of exons will form the future mRNA molecule. The nature of this phenomenon is based on the function and local that every transcript will act. These mRNA transcripts are the result of how the RNA polymerase and transcription factors interacts with DNA molecule and therefore selects the number and the size of the exons and introns of each mature mRNA transcript.
Think of it this way:
DNA inside cells store all the genetic information on a person's looks, eye colour, hair colour etc. It makes them unique. The analogy of being like books in a library basically suggests that in a library there is so much information and every book is different with different knowledge... That's basically what DNA is; millions of different information things.
Over population if i recall correctly
Tornadoes, Hurricanes, Blizzards, ect.
Megacity would probably have the biggest affect on the immediate environment and possible the outlands of the megacity as well.
