Which step caused an aerobic atmosphere during the history of earth?
a. origin of cell membranes
b. an energetic atmosphere
c. origin of anaerobic prokaryotes
d. origin of photosynthetic prokaryotes

Eristics do scientists use to distinguish between organisms in different kingdoms

Where do the respiratory and circulatory systems meet? a. in the heart b. in the muscles c. in the lungs d. in the brain

In which terrestrial biome can you find trees that produce cones instead of flowers and needles instead of leaves? have trees that produce cones instead of flowers and needles instead of leaves. the latitudes in this biome have evenly distributed precipitation throughout the year. is it high or low