Questions 44-48 Is the American Southwest, annually emerging cicadas are depende
ID: 270067 • Letter: Q
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Questions 44-48 Is the American Southwest, annually emerging cicadas are dependent upon the floodplain. Adult male cicadas the branches of the feed on the tree as shown is the food web. cotwoewood trees in the cottonwoods roots, and later perch in the cottonwood trees and chirp to antract females. Females lay their eggs in and, upon hatching,the cicada nymphs drop to the ground, barrow into the soil emerge as adults. Other organisms in the floodplain community prey on the cicadas, Kestrel Lizard Wasp Black Widow Sparrow Yellow Billed Cicada Figure 1. Food web in floodplain community Human activity has caused a decrease in the amount of flooding and an increase in the incidence of wildfires in the floodplain. In an investigation into the recent changes in the floodplain ecosystem, researchers monitored the soil temperature, amount of cottonwood ground coverage (ie, area of the ground that is shaded by leaves), and cicada emergence for a period from mid-June until late July. The results of the investigation are represented in Figure 2 and Figure 3. 7/23 7/18 7/131 7/8 7/3 6/28 6/23 28 24 20 618 6/13 l8 18 20 22 24 26 28 0 20 40 60 80 100 Cottonwood Ground Coverage (percent) Mean June Soil Temperature ("C) Figure 2. Effect of cottonwood ground coverage on soil temperature Figure 3. Relationship between soil temperature and cicada emergence date To assess the impact of wildfires on soil temperature and cicada emergence, the researchers compared mean emergence dates for two natural sites where portions had been affected by wildfire. In addition, cicada emergence was monitored at an experimental site where the soil temperature was experimentally maintained. The data are shown in the table.Explanation / Answer
44) Answer : C : Increased cottonwood growth will provide more resources for cicadas, resulting in an increase in the kestrel population.
Because, cicadas are dependent upon the cottonwood trees and they feed on the tree roots. And, kestrel is the final consumer of cicadas.
45) Answer : A : Cicadas will emerge approximately 10 days earlier
Because, ground cover of cottonwood trees decrease the soil temperature so, cicadas will emerge approx. 10 days later. When ground cover of cottonwood trees is decreased, the soil temperature will increase therefore, cicadas will emerge 10 days ealier. This is based on the table provided in the question that is when tree is unburned, cicadas emerged at July 15th and when tree is burned, cicadas emerged at July 3rd.
46) Answer : A : Wildfires caused a reduction in ground cover, which in turn caused increased soil temperature leading to earlier emergence of cicadas.
Because, cicadas need high soil temperature to grow but when trees are present, it decreases the soil temperature.
47) Answer : B : The yellow billed cuckoo population will decline because the cicadas will emerge before the hatching season begins.
Because, wildfires causes earlier emergence of cicadas.
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