13) When mRNA is "processed", what are the pieces of mRNA that are cut out and stay in the nucleus? Introns

Exons

Introns

Explanation:

The coding region of the gene is the part of the gene that is transcribed. However, not all of the gene makes the final mRNA. There are sequences called exons and introns in the coding region of the gene.

The pre-mRNA contains transcribed sequences of both the introns and exons. However, the introns are removed from the final mRNA by splicing. The final mRNA that is translated to the protein only contains exons. An illustration is attached to illustrate this.

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.