Stephanie OkparaAugust 27, 2009

AP Biology- Pd. 1Free-Response Question 4

The participants in the symbiotic relationship pertaining to plant root nodules are rhizobium and legumes. The host is the legume and the symbiont is the rhizobuim. This relationship is a mutual relationship meaning that both organisms benefit from the relationship. Rhizobium live in the host plant’s root cells and bind nitrogen from the air in the nodules. In exchange for this service, the bacteria receives high-energy carbohydrates produced in photosynthesis.

One example of the symbiotic relationship of the digestion of cellulose is the termite. The participants in this relationship are termites and protists, which reside in the termite’s intestines. This relationship is also mutual. The protists digest the cellulose contained in wood which helps the termite digest it otherwise the termite would die from a lack of nutrition. In return, the termite provides food and refuge for the protist.

The participants in the symbiotic relationship of epiphytic plants are epiphytes and various mosses, ferns, bromeliads, orchids, and other plants. The relationship is commensal meaning that one organism benefits and the other is unaffected. Epiphytes grown on sturdier plants and obtain nutrients from rainwater, decaying leaves, and sunlight and not from the host.

The two participants in the relationship of AIDS are the human (host) and the virus (symbiont). This is a parasitic relationship, a relationship where the symbiont benefits at the expense of the host. This virus reduces the effectiveness of the immune system and leaves the individual vulnerable to infections and tumors. This causes the human to slowly deteriorate.