Splicing occurs in the nucleus of a cell. DNA contains regions called introns and exon. The Introns have to be removed because if they weren't they would be translated into non-functioning proteins. A process called RNA splicing removes these introns and splices exons together. snRNAs form an RNA protein complex called a spliceosome that cuts the pre-mrna and releases the introns and joins the ends of the exons together to produce mature mRNA. Alternative splicing is a process for generating different mature mRNA from a single gene by splicing together different sets of exons during RNA processing
They bind to an allosteric site which induces a conformational change that increases the affinity of the enzyme's active site for its substrate. This increases the reaction rate.
Natural selection is when the organisms that have the better adaptation so they survive. In this case, the green was the better adaptation so they lived.