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Biology
10 original practice questions. Open them in any order.
Independent preparation material, not an official test or score prediction.
Oxygen and insect larvae below a wastewater outlet
Passage type: Data Representation
Harrow Creek receives treated water from a wastewater plant. The treated water is warmer than the creek, and it carries dissolved nutrients that feed microbes; as these microbes multiply, they consume dissolved oxygen (O2). On the same summer morning, ecologists sampled the streambed at 1 site upstream of the plant's outlet and at 5 sites downstream of it. At each site they measured water temperature and dissolved O2 concentration, and they counted 2 kinds of insect larvae in a 1 m2 area of streambed: mayfly nymphs, which take in O2 through gills and are generally sensitive to low O2, and midge larvae, which are generally tolerant of low O2.
Table 1
| Site | Distance from outlet (km) | Water temperature (°C) | Dissolved O2 (mg/L) | Mayfly nymphs (per m2) | Midge larvae (per m2) |
|---|---|---|---|---|---|
| U | 1.0 upstream | 14.0 | 9.6 | 120 | 30 |
| D1 | 0.5 downstream | 17.0 | 4.2 | 6 | 410 |
| D2 | 1.0 downstream | 16.5 | 5.1 | 18 | 330 |
| D3 | 2.0 downstream | 16.0 | 6.4 | 45 | 210 |
| D4 | 4.0 downstream | 15.0 | 7.9 | 88 | 90 |
| D5 | 8.0 downstream | 14.5 | 9.1 | 112 | 40 |
Question 1 of 10 · easier
Science passage set — Data Representation (multiple choice, 4 options)
Read the science passage and answer the question. Choose the ONE best answer from the four choices. Calculators are not permitted.
According to Table 1, as distance downstream from the outlet increased from 0.5 km to 8.0 km, the dissolved O2 concentration:
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