Which type of microorganism thrives in low concentrations of Fe2+, high concentrations of O2, and a neutral pH?

• A. Bottom-dwelling microorganisms
• B. Floating phytoplankton
• C. Deep-sea bacteria
• D. Surface algae

Answer: (A)

The correct answer is that bottom-dwelling microorganisms thrive in these specific environmental conditions. These organisms are often found in sediment or on the bottom of aquatic environments, where they can adapt to the availability of nutrients and conditions present in the water above them.

In low concentrations of Fe2+, which is essential for many biochemical processes including enzyme function, bottom-dwelling microorganisms can still thrive compared to others that may require higher concentrations. Additionally, these organisms often exist in environments with plenty of oxygen, as certain bottom-dwelling microorganisms can tolerate or even require aerobic conditions for their metabolism. The neutral pH also supports a wider range of microbial life, allowing various bottom-dwelling microorganisms to flourish in this balanced environment.

The other options do not align as closely with the specific conditions described in the question. Floating phytoplankton, for example, is more dependent on various factors including light availability for photosynthesis, while deep-sea bacteria typically thrive in high-pressure and nutrient-limited environments, not necessarily in a neutral pH. Surface algae tend to prefer shallow waters where they have immediate access to sunlight, making them less suited for the conditions described.