Which of the following statements about the phosphorus cycle is true?
a.
in living organisms, phosphorus can be found in nucleic acids.
b.
phosphorus in aquatic ecosystems is only found in sediment.
c.
elevated levels of phosphorus in aquatic ecosystems is always beneficial.
d.
the soil plays no part in the phosphorus cycle.

The phosphorus is found in the nucleic acids of the living organisms. Hence, option A is correct.

Further Explanation:

Phosphorus is known to be an essential nutrient present in the macromolecules of the humans as well as other organisms. This also includes DNA. Phosphorus cycle is slow and most of it exists in the form of phosphate ion. It is often known to be a limiting nutrient and hence, restricts the growth in the aquatic ecosystems. Phosphorus is highly essential nutrient for living organisms and the key part of nucleic acids such as DNA and of the phospholipids which make the cell membranes. It also makes up the supportive elements of the bones just like calcium phosphate.

Phosphate is mainly found in the sedimentary rocks and as the rocks weather-wear down and over a long time periods, the phosphorus slowly leaches into the water and soil surfaces. Mineral dust, volcanic ash, and aerosols may be considered as significant sources of phosphorus. Phosphate elements found in the soil can be extracted by the plants and from there it may move to animals which eat the plants.

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Answer Details:

Grade: High school

Subject: Biology

Chapter: Nucleic Acids

Keywords:

Phosphorous, phosphorus cycle, phosphates, animals, plants, soil, water surfaces, aquatic organisms, living organisms, DNA, nucleic acids.

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.