Which combination of factors will produce the highest rate of population growth?
a. high life expectancy and high infant mortality
b. low life expectancy and low infant mortality
c. low life expectancy and high infant mortality
d. high life expectancy and low infant mortality

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.

What are the doorways into and out of cells, attached to the membrane, and built in the rough er.

Which statements about the fluid mosaic structure of a membrane are correct? select the three correct statements. which statements about the fluid mosaic structure of a membrane are correct? select the three correct statements. the framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center. because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane. the diverse proteins found in and attached to membranes perform many important functions. the kinky tails of some proteins keep the membrane fluid by preventing the component molecules from packing solidly together. membranes include a mosaic, or mix, of carbohydrates embedded in a phospholipid bilayer.