How does natural selection lead to evolution? a. variations accumulate among surviving members of the species over time. b. environmental changes favor the weaker members of the species. c. overproduction provides food for stronger members of the species. d. stronger offspring kill weaker members of the same species?

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.

19. a cell is viewed under a microscope and is found to have two nuclear envelopes and spindles that appear to be breaking apart. which phase of mitosis is the cell most likely in? a. metaphase b. prophase c. telophase d. anaphase

Yeast cells reproduce quickly by budding. this is a form of reproduction so all the yeast cells a) sexual; vary b) asexual; vary c) asexual; are identical d) sexual; differ from the parents submit hint structures and functions of cells cellular reproduction