Feedback always occurs when

A.
the input of a system comes back to influence the output of and processes involved in that system.
B.
the output of a system comes back to influence the subsequent functioning of that system.
C.
no new raw materials are added to the system.
D.
no products or wastes are formed by 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.

Jasmine, at 33 months of age, is able to engage in some self-care behaviors but still has trouble with tasks such as putting on socks. a few months later, she accomplishes this same task relatively easily. the change in abilities is most likely due to

The law of thermodynamics states that energy can't be created or destroyed. to natural sources of energy on earth are the