Put the following steps of meiosis in the correct order

i. chromosomes align in the center of the cell
ii. the cell divides into haploid daughter cells
iii. spindle fibers separate chromatids
iv. the cell divides into diploid daughter cells
a. ii, iii, i, iv
b. iv, ii, iii, i
c. i, iii, iv, ii
d. iv, i, iii, ii

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.

Based on the observation that only male crickets produce a song, you hypothesize that a male's song is a form of communication to potential mates. you set up a simple experiment to test this hypothesis. in the laboratory, you place a male snowy tree cricket in enclosure a, which is adjacent to enclosureb. in enclosure b, you place other insects, one at a time, and observe their responses to the male's song. the enclosures are designed so that the two insects being tested cannot see or smell each other, but sound is transmitted from enclosure a to enclosureb.

Stem cells found adult tissue such as in bone marrow brain muscle skin and liver are only capable of what