28. If the hypothesis mentioned in the second sentence of the passage is correct, which of the following would be the most immediate result of fertilizing the waters of the Southern Ocean with iron?
Answer: E
An enhancement of photosynthesis by phytoplankton in the Southern Ocean
Fertilizing the waters of the Southern Ocean with iron would most immediately result in an enhancement of photosynthesis by phytoplankton. This is directly linked to the hypothesis that the low concentrations of phytoplankton are due to an iron deficiency, implying that adding iron would allow these organisms to thrive and increase their photosynthetic activity.
A) An introduction of new marine species into the Southern Ocean
Introducing iron into the Southern Ocean would not lead to the immediate introduction of new marine species. The focus of the hypothesis is on the existing phytoplankton populations and their ability to utilize available nutrients, not the emergence of new species.
B) A decrease in the temperature in the waters of the Southern Ocean
While increased phytoplankton growth could potentially have broader ecological effects, the immediate result of iron fertilization would not be a decrease in water temperature. This option misrepresents the relationship between phytoplankton growth and temperature changes.
C) A reduction of the amount of greenhouse gas in the Earth's atmosphere
Although enhanced photosynthesis by phytoplankton could eventually lead to a reduction in atmospheric greenhouse gases, this is a longer-term effect. The most immediate result of adding iron is the stimulation of phytoplankton growth, not a direct reduction in greenhouse gases.
D) A lowering of the concentration of phytoplankton in the Southern Ocean
This option contradicts the hypothesis presented in the extract. If iron is added and phytoplankton can effectively utilize nutrients, we would expect an increase, not a decrease, in their concentrations.
E) An enhancement of photosynthesis by phytoplankton in the Southern Ocean
This is the correct answer as fertilizing the Southern Ocean with iron directly addresses the hypothesis of iron deficiency limiting phytoplankton growth. Enhanced photosynthesis would be the immediate effect of providing this necessary nutrient.
Conclusion
The correct answer, E, directly aligns with the hypothesis that iron deficiency is limiting phytoplankton growth in the Southern Ocean. Other options either misinterpret the effects of iron fertilization or describe outcomes that are not immediate results, affirming that enhancement of photosynthesis is the most direct consequence of this intervention.