Natural selection could not occur without?

Microorganisms are involved in each of the following processes excepta. smog production.b. food production.c. infection.d. o2 production.e. decomposition of organic material.

Match each description to the appropriate biome. tropical savanna desert tropical rain forest taiga tundra has sparse vegetation and very cold temperatures located near the equator and contains trees that form dense canopy layers is very hot and dry, and has plants that need little water has cold winters, heavy snowfall and is dominated by conifers has warm temperatures and is dominated by grasses

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