Review the images of the two biomes, the tundra and the taiga. Notice that while there are about 1,700 kinds of plants there are virtually no tree species in the tundra. What are the limiting factors in preventing the immigration of tree species into the tundra? All BUT ONE could apply.

A) rocky, poor soil
B) very short growing season
C) the presence of permafrost
D) winters are six months long

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.