A diagram representing the relationship between photosynthesis and cellular respiration is shown below. The numbered boxes in the diagram represent which of the following?
1 - water; 2 - nitrogen
1 - nitrogen; 2 - oxygen
1 - Carbon dioxide; 2 - water
1 - oxygen; 2 - Carbon dioxide

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 topographic map of mt. st. helens, what is the contour interval of the volcano about height is 2,950 m?

Sarah and john are having a discussion on genetic diversity. sarah believes that it happen over a long period of time. john it happens immediately. who is correct? a. sarah is correct because genetic diversity occurs over a long period of time. b. john is correct because genetic diversity occurs immediately. c. both are correct because genetic variation can occur or long period of time. d. neither are correct because genetic diversity occurs over any period of time