Ecology of Protists

Free Response

How does killing Anopheles mosquitoes affect the Plasmodium protists?

Hint:

Plasmodium parasites infect humans and cause malaria. However, they must complete part of their life cycle within Anopheles mosquitoes, and they can only infect humans via the bite wound of a mosquito. If the mosquito population is decreased, then fewer Plasmodium would be able to develop and infect humans, thereby reducing the incidence of human infections with this parasite.

Without treatment, why does African sleeping sickness invariably lead to death?

Hint:

The trypanosomes that cause this disease are capable of expressing a glycoprotein coat with a different molecular structure with each generation. Because the immune system must respond to specific antigens to raise a meaningful defense, the changing nature of trypanosome antigens prevents the immune system from ever clearing this infection. Massive trypanosome infection eventually leads to host organ failure and death.

Describe how increasing stress to the ocean would affect a food chain containing zooxanthellae, corals, parrotfish, and sharks.

Hint:

Ocean stresses, such as rising temperatures or increasing levels of pollution, cause corals to expel their zooxanthellae symbionts. This leads to coral bleaching, and death if no new zoocanthellae colonize the corals. The dying corals will decrease the food source available to parrotfish, so the parrotfish population will decline. With fewer prey animals available, the shark population in the area will also decline.