I believe it’s gamete. Genotypes are traits that are genetic inherited. Phenotypes are traits you learn. Zygotes are a fertilized female egg.
The part of the phospholipid bilayer that interacts with water would be the hydrophilic portion consisting of the polar phosphate group. The hydrophobic tails which are the fatty acid chains will not interact with the water present in the aqueous environment.
Mutation can be both beneficial and harmful.
A very common beneficial mutation is camouflage and natural selection. The organism will acquire the change and pass it on to their offspring.
A harmful mutation can be diseases or a common harmful mutation, Down syndrome. Which gives a person an extra chromosome.