Elias conducted an experiment about the effects of exercise on the heart rate of teenagers. before morning basketball practice, he asked the members of his high school team to be his subjects. he measured each of their heart rates before and after a set of exercises. which change would most reduce the bias of his experimental design?

Even though the ostrich is a flightless bird, ostriches still possess wings that stretch approximately two meters across when fully extended. scientists speculate that when dinosaurs became extinct, some of the birds that lived during that time became land dwellers since they were able to consume the food that the dinosaurs once ate. over time, these species grew larger and heavier. eventually, the ostrich species became too big to fly. the wings found on ostriches are known as a. analogous structures. b. homologous structures. c. vestigial structures. d. symmetrical structures.