Ecologists study how living organisms interact with the chemical and physical factors of their non-living ____________. A group of interbreeding organisms of one species coexisting in the same habitat at a given time is termed a ____________. The collection of all the different interacting populations of various species within that habitat forms a ____________.

To investigate the distribution of non-motile or slow-moving organisms, researchers often employ a square grid frame called a ____________. To prevent investigator bias and ensure the sample is representative, these grids must be placed using ____________ coordinates.

By summing the counts from all sample sites and dividing by the total number of sites, researchers calculate the ____________ density per unit area. Performing a high number of replicate samples improves the ____________ of the estimate and allows researchers to more easily identify any ____________ measurements that deviate significantly from the general trend.