Scientists estimate the volume of blood in a human body to be approximately 7 percent of body weight. An average adult body with a weight of 150 to 180 pounds will contain approximately 4.7 to 5.5 liters of blood. An average child with a body weight of 80 pounds will have approximately half the amount of blood as an adult.
The amount of blood in a human body varies, depending on factors such as age, sex, overall health and even where a person lives. For example, men tend to have more blood than women of comparable size and weight.
Interestingly, people who live at high altitudes may have up to two liters of extra blood compared to those who live at lower altitudes. Because the air at higher altitudes has less oxygen, people who live at high altitudes need extra blood to deliver the right amount of oxygen to their lungs.
We know that 1 Pint = 0.473 liters
Hence, an average amount of blood in the human body = 4.7 - 5.5 lit = 10 - 12 pints.
Biological Control: This method is very effective. One pest is destroyed by another organism. For example the aphids are killed by lady beetle. The prickly pear is eradicted by cochineal insect. Here the advantage is, one does not use harmful chemicals which may get into the host plants.
AIDS: The term means Acquired Immunity Deficiency Synodrome. The virus attacks the T cells of the (white corpuscle type) blood and destroys them.
A. J . Oparin was the first to propose the origin of life from inorganic chemical atoms like Oxygen, Hydrogen, Nitrogen and Carbon.
Goitre is characterized by the swelling of the neck region. This is due to the enlargement of the thyroid gland which secretes hormone thyroxine. Thyroxine has iodine as an integral part of it. If there is not sufficient iodine in one's diet, the thyroid gland swells up.
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