Multiple choice

Which of the following statements is/are incorrect regarding the excretory function of the body?

  1. Carbon dioxide can pass across cell membranes.

  2. Proteins can act as buffers.

  3. The lungs excrete carbon dioxide.

  4. The kidney absorbs all the bicarbonate ions.

  5. There are no buffers in urine.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

There are buffers in the urine, including sodium phosphate. In addition, hydrogen ions can be excreted in the form of ammonium ions (NH4+) in the urine. The buffers are necessary because urine cannot be made very acidic because below a certain pH, the hydrogen ion gradient across the tubule wall cannot be maintained.

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