Genotype and the environment both can affect a phenotype. Phenotype= a physical feature resulting from a certain genotype.
For example, let's say a person born with a genotype pp has the phenotype: pale skin. However, if they live in a sunny environment, then the melanin in their skin will increase over time changing their phenotype to tan skin. Does that make sense as to how both factors can impact phenotype?
Meiosis only occurs in reproductive cells, as the goal is to create haploid gametes that will be used in fertilization. Meiosis is important to, but not the same as, sexual reproduction. Meiosis is necessary for sexual reproduction to occur, as it results in the formation of gametes sperm and eggs.