Question

Why do we have 2 kidney's even if we can survive on 1? I need a proper answer so answer ho knows it properly .

Answer 1

Hello 
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One answer is for symmetry

And yes we can survive on one kidney but the efficiency wont be taken as we have two kidneys which will able to absorb all blood which is pure and all helpful nutrients from it and remove the dirty blood and unwanted materials .By two kidneys we got efficiency 
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Answer 2

HII HERE YOUR ANSWER

Two kidneys are located towards the back of the lower parts of the abdominal cavity, one on either side of backbone. Left kidney is slightly larger and placed a little higher than the right kidney because of the larger size of the right lobe of the liver.
Two kidneys can effectively remove waste materials from the blood and to control the amount of water absorbed and the amount passed to the urinary bladder for excretion in the form of urine.​

If one fails by any reason, then the other can maintain the function, so that waste doesnot accumulate within the body. This is the advantage of having two kidneys.


HOPE ITS HELPS