Final answer:
The most abundant organic solute waste material in urine is urea, which is produced from the metabolism of proteins. Urea, along with other wastes, is concentrated in the urine as water is reabsorbed in the kidney's nephrons.
Step-by-step explanation:
The most abundant organic or voluminous solute waste material in urine is urea. Urea is a non-toxic molecule produced from ammonia and carbon dioxide as a by-product of the metabolism of proteins. In the glomerulus of the kidney, solutes and water are filtered from the blood. Approximately 82% of this water is reabsorbed, while urea and other metabolic wastes, such as creatinine, are concentrated in the urine.
Within the nephrons of the kidneys, mechanisms like active transport and diffusion are used to recover solutes necessary for the body. Urea, along with substances like uric acid and excess water and mineral ions, are then eliminated as part of the urine. Urine itself is a complex fluid where urea is the primary nitrogenous waste product, signifying its role as the primary solute in urine composition.