2016年11月IB生物SL真题下载-Paper2
1. Beavers are large rodents that live in waterways throughout the northern hemisphere. Dams made by beavers change the temperature of the streams and affect the mayfly, Baetis bicaudatus. In the summer of 2008, beaver ponds in West Brush Creek and Cement Creek, Colorado, were studied to evaluate their impacts on mayflies. The study sites included streams flowing into (upstream) and out of (downstream) each beaver pond.
Mayflies, including the species B. bicaudatus, are aquatic insects that hatch and spend their larval stages in water emerging from the water as adults. Larger females produce an increased number of better quality eggs.
The table shows the mean temperature differences (downstream – upstream) and mean dry mass for female and male mayflies.
(a) Calculate the difference in the mean dry mass of mayflies upstream and downstream of Cement Creek pond 9 for female and male mayflies.
I. Female: . . . . . mg
II. Male: . . . . . .mg
(b) Describe the effect dams have on water temperature.
The graph shows the mean dry mass of mayflies relative to the water temperature in their habitats.
(c) Using the graph, discuss evidence for the hypothesis that mayflies grow to greater dry mass in cooler water.
2016年11月IB生物SL真题余下省略！
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