The transfer of fluid from the glomerulus to Bowman’s capsule A. results from active transport B. transfers large molecules as easily as small ones C. is very selective as to which sub-protein-sized molecules are transferred D. usually includes the transfer of red blood cells into Bowman’s capsule E. is mainly a consequence of blood pressure in the capillaries of the glomerulus
The Correct Answer and Explanation is:
The correct answer is E: is mainly a consequence of blood pressure in the capillaries of the glomerulus.
Explanation:
The transfer of fluid from the glomerulus to Bowman’s capsule is known as glomerular filtration. This is a key step in the formation of urine and is driven primarily by the hydrostatic pressure (blood pressure) in the capillaries of the glomerulus. Here’s why option E is the correct one:
- Blood pressure in the glomerulus generates the force necessary to push plasma from the blood into the Bowman’s capsule. This is the filtration process, where water, small solutes, and waste products are filtered out of the blood, while large molecules like proteins and red blood cells remain in the blood due to their size.
- A. Results from active transport: This is incorrect because glomerular filtration is a passive process. It does not require energy or active transport mechanisms. Instead, it relies on the physical force of blood pressure.
- B. Transfers large molecules as easily as small ones: This is incorrect because the glomerulus acts as a filter, preventing large molecules (such as proteins and blood cells) from passing into the Bowman’s capsule. Only small molecules, like water, glucose, urea, and electrolytes, are freely filtered.
- C. Is very selective as to which sub-protein-sized molecules are transferred: While it’s true that the glomerulus is selective, this option is somewhat misleading. It doesn’t have the fine selection capabilities of active transport mechanisms, but rather relies on size and charge of the molecules. Small molecules pass through, while larger molecules are largely blocked by the filtration barrier.
- D. Usually includes the transfer of red blood cells into Bowman’s capsule: This is incorrect. Red blood cells are too large to pass through the filtration barrier under normal conditions. Their presence in the urine would indicate some form of pathology, such as glomerulonephritis or other kidney issues.
Thus, blood pressure in the capillaries is the main driving force behind the movement of fluid from the glomerulus into the Bowman’s capsule.
