In your textbook, what is the lower frequency of sickle-cell anemia among present day americans of west african ancestry, as compared to people living in west africa, attributed to?.

How do tides affect the organisms living in intertidal zones? a. no organisms live in intertidal zones due to the tumultuous environment. b. the mechanical forces of the waves keeps the organisms clean. c. only plants live in intertidal zones because the animals float away with the waves and never return. d. the mechanical forces of the waves can dislodge the organisms from their habitat.