The correct answer is 1 litre. Explanation & Key Takeaways: • Around 1 litre of blood flows through the kidneys per minute. Related Concepts: • Kidneys are an important organ as it filters excess water and harmful toxins from the blood. • Most vertebrates in the animal kingdom have kidneys that essentially perform the same function, however, they greatly differ in structure and the way they perform their function. • Every day, the average human kidney filters about 112 to 144 litres of blood to produce 0.94 to 1.7 litres of urine every day. • Around 1 litre of blood flows through the kidneys per minute. • Kidneys also produce hormones that regulate various bodily functions. • Renin is one such hormone that regulates blood pressure. • The basic, functional unit of kidneys are called nephrons and they help in filtering blood. • The kidneys are made up of millions of nephrons. • Kidney stone is a condition where minerals present in the urine clump or become crystalize, growing large enough to block the flow of urine. • The average human kidney is no bigger than a closed fist and weighs just under 0.4kgs. • Scientists have estimated that the number of nephrons present in the kidneys starts falling at 1% per year. • Once kidney disease sets in, it cannot be reversed, its effects can only be slowed down.