Which genetic disorders, caused by an extra x chromosome (xxy), is characterized by a lack of testicular development in males, effeminate features, possible mental impairment, and a thin stature? a) down's syndrome b) turner syndrome c) sickle cell anemia d) klinefelter's syndrome

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

Which is a function of vascular tissue? a. to perform photosynthesis b. to transport water and nutrients c. to absorb minerals and sugar d. to interact with soil fungi

Awolf pack hunts,kills, and feeds on a moose. in this interactions, the moose is a?