Copies of chromosomes are called 1) platelets.

2)sister chromatids.

3)stem cells.

4) macrophages.

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.

How is the carbon cycle related to global warming ?

Which of the following situations describes a adaptation for a mole? question 2 options: a mole is blind and cannot see underground. a mole is bright and attracts the attention of predator birds. a mole has a sensitive sense of smell to it find food underground.