Why might you use a plastic replica of a cell in biology class instead of real cells  ?

Which of the following is the most likely result of converting forestland to urban development? a. the amount of land available for lumber production decreases. b. fewer trees are needed because cities are made mainly of concrete. c. people discover more efficient ways to grow trees. d. the price of lumber goes down.

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.

Human genes only differ by less than percent. a. 1 b. 6 c. 11 d. 16