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  4. About 98 percent of the mass of every living organism is composed of just six elements including carbon, hydrogen, nitrogen, oxygen and

Q. About 98 percent of the mass of every living organism is composed of just six elements including carbon, hydrogen, nitrogen, oxygen and

 2476  189 AIPMTAIPMT 2007Biomolecules Report Error

Solution:

The plant ash reveals the presence of 40 elements but all are not essential for plant nutrition, only a few are essential for growth and development of plants. These are called as the essential elements. The essential elements may be grouped as major elements or macronutrients and trace elements or micronutrients, based on their requirement by plants. The macronutrient elements are required in large amounts and form the plant constituents. The major elements are otherwise also known as macronutrients. These include carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium and sulphur. Of these approximately ninety percent of plant body is made of carbon, hydrogen, oxygen, nitrogen, calcium and phosphorous. So, the correct answer is 'Calcium and phosphorus'