The gene has a mutation and is changed to the sequence below. GAC GGA CGA TTA
I
What kind of mutation is this?

What kind of mutation - "simple base substitution" or "point mutation".  

New mRNA strand - CUG CCU  GCU AAU

Does the mutation affect the protein. - yes because one amino acid is different

Explanation:

one characteristic that is shared by all is a soft body. many

of these invertebrate animals also have an outer shell to protect their

body. oysters, clams, snails, and mussels are all mollusks. so are octopuses, squids, and slugs. mollusks live on land and in freshwater.