Who lives in a sediment under the…ocean?
Today’s ACT question of the day is a science question from the passage about sediment in the bottom of the ocean. This time, we need to find the depth that would be a good home for a creature that likes low concentrations of Fe2+, high concentrations of O2, and a neutral pH. Looking back at our data table, we need to find a row that has low concentrations of Fe2+, high concentrations of O2, and a neutral pH.
| Depth (cm) |
Temperature (oC) |
pH | Concentration in sediment (ppm) | |||||
| SO42– | S2– | CO2 | Fe3+ | Fe2+ | O2 | |||
| 0 | 4 | 7.0 | 7.0 | 0.0 | 1.0 | 4.0 | 0.5 | 2.0 |
| 5 | 5 | 6.5 | 5.0 | 2.0 | 1.5 | 3.0 | 1.5 | 1.0 |
| 10 | 7 | 6.0 | 3.5 | 3.5 | 2.0 | 2.0 | 2.0 | 0.0 |
| 15 | 9 | 5.5 | 3.3 | 3.8 | 3.0 | 0.8 | 3.8 | 0.0 |
| 20 | 10 | 5.0 | 3.0 | 4.0 | 1.0 | 0.5 | 4.0 | 0.0 |
The first row has high O2 and low Fe2+, so whether or not you remember that 7 is the neutral pH, the first row is the best choice. This corresponds to a depth of 0cm (left column).