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Elemental Composition of Living Matter
Concepts tested here
- Major elements of the body
All Questions
2007 AIPMT-PRE 1 question
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About 98 percent of the mass of every living organism is composed of just six elements including carbon, hydrogen, nitrogen, oxygen andOnly a few elements make up almost the whole mass of a living organism.
Oxygen (about 65 percent), carbon (about 18.5 percent), hydrogen (about 9.5 percent) and nitrogen (about 3.3 percent) together make up about 96 percent of the body mass.
The next most abundant elements by mass are calcium (about 1.5 percent) and phosphorus (about 1 percent).
Calcium and phosphorus are present in large amounts in bones and teeth; phosphorus is also a part of nucleic acids, ATP and phospholipids.
These six elements together account for about 98 to 99 percent of the mass.
Sulphur, sodium and magnesium are each present in amounts of less than about 0.3 percent.
So, going by mass, the two remaining elements are calcium and phosphorus, as given in the answer key.