How do hosts relate to the life cycle of a parasite?

Hosts play a crucial role in the life cycle of a parasite primarily by serving as a source of nutrition. Parasites rely extensively on their hosts for sustenance, as they obtain the necessary nutrients to grow, reproduce, and complete their development. This relationship is often one of dependency, where the parasite has adapted to exploit the host's bodily functions and resources for its own benefit, leading to a parasitic relationship that can impact the health of the host.

While other aspects exist, such as competition for resources or attempts by the host to eliminate parasites, the defining characteristic of the relationship—especially in the context of support for the parasite's life cycle—centers around the nutritional support that hosts provide. This relationship facilitates the parasite's continued existence and proliferation.