Filtrate in the Bowman’s capsule contains vitamins because

Analyze the question: The question asks why vitamins appear in the glomerular filtrate in the Bowman's capsule.

Concept: Ultrafiltration Blood enters the glomerulus at high pressure. The glomerular capillaries and the Bowman's capsule lining (podocytes) act as a filter. Only substances that are small enough can pass through. Whether a substance gets filtered depends on its molecular size, not on what the body needs afterwards.

• Small molecules pass through: water, glucose, amino acids, urea, mineral salts, vitamins
• Large molecules stay in the blood: plasma proteins, red blood cells, white blood cells, platelets

Step by step on the options:

• A. "Only a little amount is required by the body" is wrong. Filtration does not depend on how much the body needs.
• B. "They can be reabsorbed into the blood" is true, but it explains what happens later in the nephron tubule (selective reabsorption). It does not explain why they are present in the filtrate in the first place.
• C. "They have low molecular weight" is correct. Vitamins are small molecules, so they pass through the filtration membrane with the water and other small solutes.
• D. "Most of them are fat soluble" is wrong. Many vitamins (B and C) are water soluble, and fat solubility has nothing to do with ultrafiltration.

Answer: Option C.

Exam tip: Remember two separate processes: filtration depends on size (in the Bowman's capsule), and reabsorption depends on usefulness (in the tubules). If a question asks why something is in the filtrate, think "small size." If it asks why it is not in the urine, think "reabsorption."