Which is evidence that a chemical reaction has occurred

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -

Which of the following shows the results that you would get if you tested beef using the four tests in the gizmo

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.