Suggesty why water has to be pumped directly to the plant roots, rather than just poured

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.

Creation of an unnaturally uniform sample to represent a diverse populationcan be avoided by: a. including only willing b. asking another scientist for .c. choosing only identical participants.d. selecting individuals at random.

Q: a: in sexually reproducing animals, once fertilization of the egg takes place, the exists as a single cell until cell division begins