If you were attempting to tell whether an animal produces its primary urine by ultrafiltration or secretion, what measurements would you make on the primary urine? If your measurements indicated that ultrafiltration might be occurring, what other types of measurements would you make to determine whether physical and physicochemical conditions favorable to ultrafiltration exist? Explain.

The first analysis to urine will be if there is presence of blood cells or macro molecules.

Explanation:

In filtration, since the urine pass trough a membrane, only small molecules could pass like glucose, amino acids, and urea.

If the urine is produce by secretion like in some insects, leeches, or teleost, then the movement of the molecules is due the osmotic pressure, so the ions are the present in the urine.

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