Question

Some investigators predict that the continued use of chemical fertilizers will have the long-term effect of changing nutrient ratios in aquatic systems. Specifically, they predict that the ratio of phosphorus to nitrogen will increase and the ratios of both nitrogen and phosphorus to silica will increase.
Based on your experiments, which of the following would be the most likely outcome of this shift in nutrient ratios?

A) Diatoms will be least favored, but insufficient information is provided to determine whether green algae or cyanobacteria will be favored.
B) Cyanobacteria will be favored over green algae and diatoms, but insufficient information is provided to determine whether green algae or diatoms will be favored.

Answer 1

Answer:

A) Diatoms will be least favored, but insufficient information is provided to determine whether green algae or cyanobacteria will be favored.

Explanation:

In a habitat where the ratios of both nitrogen and phosphorus to silica is high, diatoms will be least favored.

Diatoms are a group of unicellular algae whose cell walls are made up majorly of silica. They absorb silica in their nutrition and use it to build their cell walls.

While the enrichment of aquatic systems with phosphorus and nitrogen generally favor the growth of algae and causes what is known as algal bloom, a commensurate amount of silica in the aquatic system will be needed for diatoms in order for them to build their cell walls.

Hence, while there is no sufficient information to conclude whether green algae or cyanobacteria will be favored, lack of commensurate increase of silica along with phosphorus and nitrogen in the aquatic system will ensure that diatoms are least favored among the three groups of algae.

The correct option is A.