- The Nitrogen Cycle
Nitrogen is an important element in
It makes up
almost 80% of earth's _ and is required by organisms to make
_. Atmospheric nitrogen cannot be used by
living things so it must be converted into usable forms. The nitrogen
cycle is the movement of nitrogen through the food chain from
simple
_(not made from living things) compounds into
complex _
(made from living things) compounds.

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.

Many humans consume both plants and animals. these humans are considered to be which of the following? herbivores carnivores omnivores

Match the following terms and definitions. the transformation of a larva to an adult; occurs only in animals having great differences in form between the larva and adult pupa 2. type of mammal that lays eggs monotreme nymph the part of certain insect life cycles in which the young animal has no wings or reproductive organs the developmental stage between larva and adult in insects undergoing metamorphosis metamorphosis 5. the male gonad which produces sperm testes