Plants make via photosynthesis using , which is a by–product of many organisms during respiration. a. H2O, CO2
b. CO2, O2
c. O2, CO2
d. O2, H2O

Which greenhouse gas is emitted when burn fossil fuels for energy? a. nitrogen b. oxygen c. carbon dioxide d. helium

Number and variety of living organism; includes genetic, species, and ecological types

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