If a scientist wants to figure out how old a rock layer is, would it be useful to use a substance that takes a long time to break down (has a long half life), or a substance that breaks down quickly? is it A. A substance that breaks down slowly, because then there won't be enough left to measure

B. A substance that breaks down slowly, because then there will be enough left to measure.

C. A substance that breaks down quickly, so it will be all gone and we'll know it's old

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.

Matched chromosomes carrying information about the same characteristics in the organism are called

Describe the impact of deforestation of both abiotic and biotic factors within the tropical rainforest.