Humans need to remove (excrete) waste products from the bloodstream. Describe the processes that produce waste products and how the products are removed from the body. (6 marks)

Urea is produced via the breakdown of amino acids in the liver, which is removed from the blood by the kidneys and excreted in urine. Carbon dioxide is a waste product of respiration in cells and is breathed out from the lungs. Water is also a waste product of respiration in cells. It can be excreted from the lungs in expiration, through sweat from the skin, and as urine from the kidneys.
Toxins are broken down in the liver and the products are removed by the kidneys into urine. Excess ions from eating and drinking are removed via the skin through sweat, and by the kidneys and excreted as urine.