List of top Ecology and Evolution Questions on Ecosystems

Excess fertilizers used in agriculture commonly end up as runoff and cause phytoplankton blooms in rivers. To figure out whether these blooms were driven by ammonium or phosphate fertilizers, researchers cultured a phytoplankton species in multiple samples of unpolluted river water. The samples were divided equally among three treatments: ammonium fertilizer added, phosphate fertilizer added, and no fertilizer added. They then measured phytoplankton density in each of the samples after a week. Phytoplankton densities (in thousands of cells/ml) are reported in the table shown.
Which one of the following is not an expected impact of global warming?
Which one of the following represents the chemical energy available to herbivores in an ecosystem?
Which one of the following statements is true with respect to energy requirements of photosynthesis in C3 and C4 biochemical cycles?
Grazing by large mammalian herbivores can have a strong influence on ecosystem structure, and can cause ecosystems to transition between alternative states over decades. Which one of the following transitions can result from grazing?