Tropical rain forests contain diverse communities of organisms with many interesting relationships. One such relationship connects parasitic fungi and their insect hosts. A type of parasitic fungus, called Ophiocordyceps unilateralis, disperses spores onto the forest floor, but cannot successfully grow on the ground. The fungus requires specific conditions and must grow inside of a specific ant species, called the host, to reproduce. The ants, various species of carpenter ant, make nests in the trees.

O. unilateralis feeds on and grows inside the insect host, and within a few days the fungus affects the insect’s brain. The insect exhibits unusual behaviors such as wandering away from the colony to where light and humidity favor fungal growth. Just before dying, the insect bites into and firmly attaches itself to a plant. Then, the fungus slowly grows outward from the dead insect’s head, producing a pod of spores that eventually bursts open. The spores fall to the ground, restarting the life cycle of the fungus.

Though this relationship may sound gruesome, researchers note that these parasitic fungi may help maintain biodiversity in the tropical rain forest. Some parasitic fungi may be host-specific, meaning that a fungus species only infects a particular type of insect. Scientists have observed that if an insect population begins to grow, more fungal infections occur, and then the insect population levels off again. This relationship may prevent overpopulation of the habitat by any one insect species.

Short Answer Item: 3 point value

Question Overview:In this short answer question, you are required to cite specific textual evidence and develop a logical argument. You must select and present evidence from the stimulus and then produce a line of reasoning in order to compose a response for this question. You must also use your understanding of ecosystems and life cycles in order to explain how deforestation can be disruptive. This question tests your skill at the complex task of using, producing, and justifying an argument by incorporating elements from the text into the presentation of your own ideas.

Scoring Guide:Each of the boxes below lists the elements that would need to be present in your response in order to obtain the specified score. After you review these descriptions, click on each of the Example tabs above to review actual test-taker responses along with explanations of why each response received the score that it did.

3-Point ResponseResponse contains
a clear and well-developed explanation of how deforestation could disrupt the life cycle of Ophiocordyceps unilateralis in tropical rain forests
complete support from the passage

2-Point ResponseResponse contains
an adequate or partially articulated explanation of how deforestation could disrupt the life cycle of Ophiocordyceps unilateralis in tropical rain forests
partial support from the passage

1-Point ResponseResponse contains
a minimal or implied explanation of how deforestation could disrupt the life cycle of Ophiocordyceps unilateralis in tropical rain forests
minimal or implied support from the passage

0-Point ResponseResponse contains
no explanation of how deforestation could disrupt the life cycle of Ophiocordyceps unilateralis in tropical rain forests
no support from the passage

Example 1

3-Point Response

Deforestation destroys the environment where thousands of species of animals flourish including Ophiocordyceps. Ophiocordyceps rely heavily on the environment to survive for two major reasons. First of all, Ophiocordyceps often find hosts in Carpenter Ants which build their nests high up in the trees of rainforests. When deforestation occurs, Carpenter Ants lose their nests and homes which would likely result in the diminishment of their species. This would disrupt the Ophiocordyceps species significantly as Ophiocordyceps cannto survive without a host - without the Carpenter Ants, there would be no Ophiocordyceps. The other reason that Ophiocordyceps would suffer is because without the trees, there would be nothing for them to climb to reach greater amounts of light and less humidity. While lack of trees would lead to more light reaching the ground, the issue of humidity affecting the Ophiocordyceps would still exist. With tall trees, the Ophiocordyceps are able to reach heights with less humidity but deforestation would leave the Ophiocordyceps without a way to escape the humidity ultimately slowing the growth of the fungus. In conclusion, deforestation would have a very significant impact on the life cycle of the Ophiocordyceps for without trees there would be no hosts for the Ophiocordyceps to grow and without a way to escape humidity there would be a slowing of growth.

Score Explanation: This 3-point response explains how deforestation could disrupt the life cycle of Ophiocordyceps unilateral is by stating, "Deforestation destroys the environment where thousands of species of animals flourish including Ophiocordyceps." This statement makes the connection between the destruction of the environment and its negative effect on the life cycle of Ophiocordyceps unilateralis. The explanation is supported with the following piece of evidence, "Ophiocordyceps often find hosts in Carpenter Ants which build their nests high up in the trees of rainforests." This piece of evidence links the trees with the living environment of the Ophiocordyceps. The explanation is further supported with a second piece of evidence, "The other reason that Ophiocordyceps would suffer is because without the trees, there would be nothing for them to climb to reach greater amounts of light and less humidity." This piece of evidence links the explanation of a loss of environment back to this statement in the passage which describes how the insects need the light and humidity because those conditions favor growth.

2-Point Response

Ophiocordyceps unilateralis feed of the carpenter ant, which nests in the trees. Deforestation will cause many carpenter ant to die because of the lack of homes. As a result 0. unilateralis lose many hosts to feed off of, and in tum reproduction is disrupted.

Score Explanation: This response explains how deforestation could disrupt the life cycle of Ophiocordyceps unilateralis by stating, "Deforestation will cause many carpenter ant to die because of the lack of homes." This statement describes how the destruction of the habitat or "home" of the Ophiocordyceps unilateralis has a negative effect on the life cycle of Ophiocordyceps. The explanation is supported with the following piece of evidence, " .. .feed of the carpenter ant, which nests in the trees." This evidence, which is taken from the last sentence of the paragraph, provides an indirect reference as to how deforestation will destroy the "home" of the carpenter ant, which will in turn affect the Ophiocordyceps unilateralis. However, this response contains only partial support from the passage and therefore it receives a score of 2.

1-Point Response

WITHOUT THE TRESS OPHIOCORDYCEPS UNILATERALIS CANNOT GROW BECAUSE THEY NEED THE TREES TO DISPERSE SPORES ONTO THE FOREST FLOOR IN ORDER TO GROW AND REPRODUCE.

Score Explanation: This response gives an explanation of how deforestation could disrupt the lifecycle of the Ophiocordyceps unilateralis by stating, "BECAUSE THEY NEED THE TREES TO DISPERSE SPORES ONTO THE FOREST FLOOR IN ORDER TO GROW AND REPRODUCE ." The response explains how the Ophiocordyceps unilateralis requires the trees in order to continue its lifecycle. However, it does not include any supporting textual evidence from the passage; therefore, this response receives a score of 1.