That each gamete contains a single allele of the eye color gene is an illustration of

Mendel's law of segregation

Explanation:

According to MENDEL Law of segregation, it states that allele pairs that belong to given locus segregate during the process of gamete formation and they will unite at the fertilization stage. Alleles sort out independently because the location of gene is on the specific chromosome.

parasites can detrimentally affect their host, but also must not allow their host to die before they can complete their life cycle. some parasites have complex life cycles with many different hosts, and have had to find ways of persisting in many different environments during the change from one host to another. ectoparasites live outside the body of the host, and can more easily  disperse, but are  more exposed to predators, parasites, parasitoids. endoparasites live inside the body of the host, and are therefore protected from the outside environment. but they can be  attacked by the host's immune system. they have therefore developed  mechanisms for dispersal such as  complex life cycles.