Question

After millions of years, sedimentary rock containing phosphorus is uplifted from plate tectonic activity. Follow the phosphorus molecules found in the rock through the whole phosphorus cycle, by numbering the steps that would follow. 1. Step 1 The bear, after a fruitful life, dies from old age. 2. Step 2 A fish eats aquatic plants. 3. Step 3 Weathering and erosion of the rock deposits the phosphorus into water. 4. Step 4 Soil washes into a lake, where it sinks to the bottom to become sedimentary rock. 5. Step 5 Aquatic plants absorb and assimilate the dissolved phosphorus. 6. Step 6 Decomposition of the dead bear releases phosphorus into the soil. 7. Step 7 The fish is caught and eaten by a bear.

Answer 1

The following is the correct order of the whole phosphorus cycle:

1. Erosion and weathering of the rock deposits the phosphorus into water.

2. Aquatic plants absorb and assimilate the dissolved phosphate.

3. A fish consumes aquatic plants.

4. The fish is caught and consumed by a bear.

5. The bear, after a fruitful life, dies from an old age.

6. Decomposition of the dead bear discharged phosphorus into the soil.

7. The soil washes into a lake, where it sinks to the bottom to turn into a sedimentary rock.