The diagram below shows some relationships between ecosystems near the Sonoran and Chihuahuan Deserts. What happens as elevation increases?

A. Number of cacti increases.
B. Soil fertility decreases
C. Size of plants decreases,
D. Amount of rainfall increases,

How is ribosomal rna useful as a molecular clock? a. a large portion of the dna ring is not vital to structure or function, allowing it to accumulate neutral mutations. b. its rate of mutation increases over time as organisms continue to evolve and differentiate from each other. c. a slow mutation rate makes it useful for determining evolutionary relationships between ancient species. d. it is only found in select organisms, making it easier to compare relationships between species that have it.