when a scientist is conducting research about all the plants and wildlife in the Mojave desert as well as the deserts resource such as water and soil the scientist is studying

The correct answer to the following question will be "An ecosystem".

Explanation:

The environment seems to be all the species of animals and plants that people living in a defined place, including the complex nature of relationships between them because of environmental surroundings. Sometimes whenever a scientist seems to be doing work on both animals and plants throughout the desert, including on wilderness freshwater resources as well as soil.

So that the above seems to be the right answer.