Some biologists have identified symbiotic relationships in which it appears that one organism gains from the relationship while the other organism is unaffected. Although after further research, the researchers find out that both members of the relationship benefit. The researchers therefore realize that

The evolution of a new species is most like

The first essential step in changing atmospheric nitrogen into more usable NH3 is called ________ and is undertaken by symbiotic bacteria.

Use the accompanying figure to answer the following questions.Which of the following are depicted in the figure as feeding at multiple trophic levels?

Walking through a national park, you step off a well-marked trail to take a photograph and accidentally trample a rare orchid. This is an example of

Human activity has affected every aspect of the water cycle. Identify three ways that humans have altered the water cycle. What are the major concerns regarding our alteration of the water cycle?

Read the following scenario and answer the questions below. (Same prompt as before)In the early 20th century there were lush stands of tall grasses in the valleys of Arizona. Dramatic summer rainstorms dumped huge amounts of water, very quickly, on the rocky upper slopes. The water ran down the slopes and into the grasslands, where it quickly soaked into the soft, porous soil where prairie dogs were active. Cattle-ranching utilized the grasses, but the ranchers did not appreciate the multitudes of prairie dogs that lived in the grasslands. Prairie dogs constantly dug through the soil, making new burrows and eating grasses, roots and all. It was commonly believed that cattle and horses would stumble in the prairie dog holes and break their legs. In addition, many ranchers were convinced that the prairie dogs would destroy the grasses because they directly competed with the cattle for food. The ranchers had already done away with most predators that preyed on prairie dogs and might possibly affect cattle and now they turned their attention to the prairie dogs themselves. The ranchers became a part of a new federally sponsored movement to poison the grassland prairie dogs. This movement took root and spread through the 1920s and 1930s.You’ve learned about “keystone species.” How do the prairie dogs in this story meet the definition of a keystone species?

A coyote can alter its diet to match seasonal abundance of plants, fruits, or small animals and would therefore be considered ________.

Resource partitioning

Why do ecologists favor the term food web as opposed to food chain?