Which best describes the nucleus of an atom?
O A. It is made of neutrons and electrons.
B. It is the negatively charged part of the atom.
C. It is the most massive part of the atom.
O D. It contains no mass.

Which of the following will not cause mass extinction? a. drastic change is weather b. geological change c. both a and b d. none of the above

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.

The rapid decomposition of organic matter produces evidence which supports: the slow accumulation of coal deposits long ages of the earth rapid burial of vast amounts of vegetation biblical account of noah's flood