Cells need oxygen to make energy. oxygen-rich blood is transported to tissues. when the oxygen is dropped off, it needs to move through structures that are small and thin. which vessels allow for oxygen movement into the tissues? arteries veins heart capillaries

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.