Describe how the lac operon functions, and explain how it permits e. coli to produce the enzymes needed to break down lactose when it is present in the bacterium.

Name the type of chemical that speeds up digestion

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 of the following is the earliest era of earth's geologic time scale? cenozoic mesozoic precambrian paleozoic