An open system, such as an ecosystem, is characterized by which trait?

a. energy enters the system but does not leave it.

b. energy neither enters nor leaves the system.

c. energy leaves the system but does not enter it.

d. energy can enter or leave the system.

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.

If a young male's body is just beginning the process of producing sperm, when is it likely that he would ejaculate mature, viable sperm"

Locards exchange principle implies all of the following except