In the presence of ADH, The distal nephron is least permeable to :a) water .b) ammonia .c) urea .d) sodium .e) carbon dioxide

The distal nephron is least permeable to ammonia in the presence of ADH.

Here's a step-by-step explanation:

1. ADH, or antidiuretic hormone, is a hormone that helps your kidneys manage the amount of water in your body. It does this by affecting the permeability of the nephrons in your kidneys.

2. The distal nephron is a part of the nephron where fine adjustments to water reabsorption are made. It is sensitive to ADH.

3. When ADH is present, the distal nephron becomes more permeable to water, urea, and sodium. This means that more of these substances can be reabsorbed back into the body, reducing the amount that is excreted in urine.

4. However, the distal nephron does not become more permeable to ammonia or carbon dioxide in the presence of ADH. Of these two, ammonia is generally less permeable in the distal nephron.

5. Therefore, in the presence of ADH, the distal nephron is least permeable to ammonia.