AP BIOLOGY

Detailed explanation-1: -As the urine moves along the tubules of the nephrons, some useful substances like glucose, amino acids, salts, and water are selectively reabsorbed from it.

Detailed explanation-2: -glucose moves from the filtrate into the bloodstream when it is selectively reabsorbed.

Detailed explanation-3: -Selective reabsorption takes place in the proximal convoluted tubule (PCT) of the kidney. It is the process by which certain substances that are required by the body (such as glucose, amino acids, vitamins and water) but have been filtered out of the blood during ultrafiltration, are reabsorbed.

Detailed explanation-4: -Reabsorption of glucose occurs in a two step process involving reabsorption across the luminal membrane via Na-glucose cotransporter and then facilitated glucose transport across the peritubular membrane. Under 200 mg/dL, all glucose filtered into Bowman’s space is reabsorbed.

Detailed explanation-5: -Having filtered out small essential molecules from the blood-the kidneys must reabsorb the molecules which are needed, while allowing those molecules which are not needed to pass out in the urine. Therefore, the kidneys selectively reabsorb only those molecules which the body needs back in the bloodstream.