What description best explains why viruses can become more pathogenic to hosts that were not affected by the virus before?

Explain why in any given geographical region, women tend to have lighter skins( by 3-4% on average) than men?

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.

Lupe is a carrier for color blindness. her husband clifford is colorblind. if lupe and clifford have four children, what's the probability of a boy being colorblind?