Which of the following substances is least likely to be found in glomerular filtrate?

• A. Albumin
• B. Urea
• C. Sodium ions
• D. Glucose

Answer: (A)

Verified step by step guidance

1. Understand the function of the glomerulus: The glomerulus is a network of capillaries in the kidney that filters blood to form glomerular filtrate. This filtrate contains substances small enough to pass through the filtration barrier, while larger molecules are retained in the blood.
2. Review the composition of glomerular filtrate: Glomerular filtrate typically includes water, electrolytes (e.g., sodium ions), glucose, and waste products like urea. Large proteins, such as albumin, are generally too large to pass through the filtration barrier under normal conditions.
3. Consider the size and properties of the substances listed: Albumin is a large protein molecule, while urea, sodium ions, and glucose are smaller molecules that can pass through the filtration barrier.
4. Relate the filtration process to the question: Since albumin is a large molecule, it is least likely to be found in glomerular filtrate under normal conditions. The other substances listed (urea, sodium ions, and glucose) are small enough to pass through the filtration barrier and are commonly found in the filtrate.
5. Conclude the reasoning: Based on the size and filtration properties of the substances, albumin is the least likely to be found in glomerular filtrate, as it is typically retained in the bloodstream unless there is damage to the filtration barrier.