Assertion : Kidneys maintain the osmotic concentration of the blood .
Reason : Kidneys eliminate either hypotonic or hypertonic urine according to the need of the body .

Options

A. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B. If both the assertion and the reason are true and the reason is not a correct explanation of the assertion
C. If the assertion is true but the reason is false
D. If both the assertion and reason are false

Answer

A

Explanation

(a) Kidneys play an essential role in maintaining the concentration and osmotic pressure (osmoconcentration)of blood . When water intake of an animal is very high, the urine excreted has to be hypotonic i.e., dilute and lower in omotic pressure than their blood in order to remove the excess of water contrary to this, when there is a threat of excessive water loss from the body, the urine needs to be hydertonic more concentrated and higher in osmotic pressure than their blood , to reduce the loss of the water with urine . In this way , the osmotic concentration of the bloods is maintanied .