Question

Formation of urea takes place in
A. Heart
B. Kidney
C. Liver
D. Lungs

Answer 1

Hint: Urea is formed in our body by a cyclical process called Urea cycle. This process takes place inside our body in order to convert the toxic ammonia to a non-toxic urea. The urea formed is then excreted out of the body.

Complete answer:
All organisms produce ammonia in their bodies. Ammonia is formed as a by-product of protein digestion. If high concentration of ammonia accumulates in our body, it affects the neurons, thereby weakening the defensive mechanism of the brain. This can lead to fatal conditions. Therefore, it is imperative that ammonia be converted to urea and excreted from the body.
The formation of urea from ammonia is achieved by a process called urea cycle. Urea cycle takes place in the mitochondria and cytosol of the liver cells. The process takes place through five steps using various enzymes and the driving force of the reaction comes from hydrolysis of Adenosine triphosphate (ATP) to Adenosine diphosphate (ADP).
Heart is a muscular organ covered by the pericardium. The major function of the heart is to continuously pump blood into the circulatory system to maintain a continuous flow of blood in the body. The blood carries oxygen and nutrients. The complete circulation of blood is achieved by the systemic circulation and the pulmonary circulation. During the pulmonary circulation, blood moves between heart and lungs, exchanging carbon dioxide with oxygen through respiration. The oxygenated blood then transports the oxygen to different parts of the body through systemic circulation.
Kidney is the main excretory organ of the body. There are two kidneys in the body located on each side of the spinal cord. The kidneys function to remove waste particles from the body. The main excretory product of the body is urine which contains nitrogenous waste products like urea and uric acid. The kidney also maintains acid base balance, blood pressure and electrolyte balance of the body.
Lungs are the primary organ of respiration. There are two lungs located on either side of the heart in the thoracic cavity. The lungs function to transport oxygen from the atmosphere to the bloodstream and carbon dioxide from to the body to the atmosphere. This is achieved by the process of respiration.

Therefore, the correct option is (C).

Note: Ammonia is formed in our body as a result of various digestive processes. Accumulation of ammonia in high concentration can be harmful to the body. Therefore, ammonia is excreted in the form of urea. The conversion of ammonia to urea takes place in the liver through a cyclical process called urea cycle. The urea thus formed is carried to the kidneys to be excreted from the body.