In the simplest sense, expressing a gene means manufacturing its corresponding protein, and this multilayered process has two major steps. In the first step, the information in DNA is transferred to a messenger RNA (mRNA) molecule by way of a process called transcription.
This type of mutation would be called a deletion
Hope this helps :)
You'll want to double check, but I think it's (a) cotyledon.
I'm assuming that you want us to tell you what organism does these things. So it would be a plant.
