Mystery of Wexford pedigree

This is collection of data made by comparing objects in standard units. in science, the units are metric.

Afive-year study was carried out on a population of algae in a lake. the study found that the algae population was steadily decreasing in size. over the five-year period this decrease most likely led to

Asample of digestive juice was removed from the stomach of a pig. the juice was placed in a test tube along with some grains of wheat. a second test tube was set up containing an equal number of wheat grains, with distilled water rather than digestive juice. the test tubes were kept for 8 hours at 40 degrees c. after 8 hours, the grains inside the digestive juice had broken into tiny particles. the grains of wheat, in the water, were wet but otherwise unchanged. what is the control group?