[Campbell Biology P.635] Based on Figure 27.19, what is the approximate average uptake of K+... | Practice Question

Based on Figure 27.19, what is the approximate average uptake of K+ in mg for seedlings in soils with bacteria Strain 1, 2, and 3 combined ? If bacteria had no effect on nutrient availability, what would you expect this average to be?

  • A: Average with bacteria ≈ 0.65 mg; Expected without effect ≈ 0.5 mg.
  • B: Average with bacteria ≈ 0.5 mg; Expected without effect ≈ 0.65 mg.
  • C: Average with bacteria ≈ 0.75 mg; Expected without effect ≈ 0.6 mg.
  • D: Average with bacteria ≈ 0.45 mg; Expected without effect ≈ 0.7 mg.

Explanation

From Figure 27.19, approximate K+ uptake values are: Strain 1 ≈ 0.7 mg, Strain 2 ≈ 0.6 mg, Strain 3 ≈ 0.65 mg. The average for soils with bacteria is 0.7 + 0.6 + 0.65 / 3 = 1.95 / 3 ≈ 0.65 mg. The 'No bacteria' control group shows an uptake of approximately 0.5 mg. If bacteria had no effect, the average for the treated groups would be expected to be similar to the 'No bacteria' control, i.e., around 0.5 mg.