This is a symbiotic relationship between plant roots and certain fungi?

This is an example of an organism that has successfully recovered from being endangered?

How can humans pass on DDT?

A measurement of the variety of different versions of the same gene within a species?

Water saturation of soil that fills all air spaces and causes plant roots to die?

Most pathogens of the human body would be classified as 

This is a chemical that kills fungi specifically?

In this relationship the effect on one species is positive (+) and the effect on the other species is also positive (+)?

This habitat is characterized by low moisture levels, wide daily temperature fluctuations, and most animals are nocturnal and conserve water?

This is a testable statement in science?