Question

Living cell contains 60-75% water. Water present in the human body is
(a) 60-65%
(b) 50-55%
(c) 75-80%
(d) 65-70%

Answer 1

Hint: Water is extremely essential for our survival. It is involved in multiple activities which range from transport, excretion, dissolution of salts to release ions, temperature regulation to nutrient absorption.

Complete answer:
It is a good solvent and hence most of our metabolic reactions take place in water. Like hydrolases in our body are a set of enzymes that requires water to cleave a chemical bond. Insufficient water uptake causes dehydration and increases the chances of kidney stones. Many fluid secretions are composed of water like saliva, mucus which aids in digestion. Also, water is essential for the transport of oxygen throughout our body. About 65-70% of the human body is composed of water which amounts to two- thirds of our body.
So, the correct answer is ‘65-70%.’

Additional Information:
The molecules or chemicals present in the human body are known as biomolecules. They are primarily of two types - inorganic and organic. Inorganic constituents of the cellular pool are minerals, gases, and water. They do not contain carbon along with hydrogen, unlike the organic constituents. The following are the major organic constituents:
Proteins: They are polymers of amino acids that are joined into a linear sequence via a peptide bond between them. Levels of configurations involve a linear sequence followed by a secondary and tertiary structure as that in enzymes.
Carbohydrates: Their basic skeleton contains carbon, hydrogen, and oxygen in an approximate ratio of 1:2:1. A chain of monomers or monosaccharides joins to form a complex polysaccharide via a glycosidic bond.
Lipids: Lipids are the biomolecules formed by the esterification reaction of fatty acids and alcohol. They are insoluble in water but soluble in a non- polar organic solvent such as benzene.
Nucleic acids: The polymers of nucleotides are known as polynucleotides or simply nucleic acids. A nucleotide is composed of a phosphorus molecule linked to a ribose or deoxyribose sugar which is, in turn, attached to nitrogen bases via a glycosidic bond.

Note:
- Many polypeptides attain a quaternary structure to fulfill their important functions. E.g. Haemoglobin which aids in the transport of oxygen for cellular requirements.
- Carbohydrates are the basic components of food and the principal source of energy in our body. E.g. Glycogen.
- Lipids are the energy reserves of our body, constituents of receptors, and some hormones. E.g Prostaglandins.
- DNA and RNA are two nucleic acids in our body.