Why is the phosphorus cycle not considered as a real cycle?

The phosphorous cycle is not considered a true cycle because unlike the others such as the water, carbon, nitrogen and sulphur cycles,  it does not include a gas phase, although small amounts of phosphoric acid may make their way into the atmosphere contributing , in some cases, to acid rain.

Very little phosphorous circulates in the atmosphere because at Earth's normal temperatures and pressures, phosphorous and its various compounds are not gases. The largest reservoir of phosphorous is in sedimentary rock.

the answers are as following:

1. c. double helix, nucleosome, coil, supercoil, chromosome

2. b. g2 phase, preparation for mitosis

3. d. interphase consists of the g1, s, and g2 phases

4. c. metaphase

5. a. chromosomes are duplicated before cell division so that each new daughter cell has a complete set

a compound light microscope is used to magnify objects in steps.  

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