Why are the carbon cycle, the phosphorous cycle, the water cycle, and the nitrogen cycle all considered to be biogeochemical cycles?

a. because all these cycles include the organisms inhabiting water, land, and air.
b. because all these cycles include living organisms, the biosphere, and the chemical factors in them.
c. because all these cycles include nonliving organisms, the atmosphere, and the physical factors in them.
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What are the student's observations and inferences before he starts his investigation?

Which of the following is an eon in the time scale? phanerozoic proterozoic archean all of the above

Even though the ostrich is a flightless bird, ostriches still possess wings that stretch approximately two meters across when fully extended. scientists speculate that when dinosaurs became extinct, some of the birds that lived during that time became land dwellers since they were able to consume the food that the dinosaurs once ate. over time, these species grew larger and heavier. eventually, the ostrich species became too big to fly. the wings found on ostriches are known as a. analogous structures. b. homologous structures. c. vestigial structures. d. symmetrical structures.