Biologists have been able to produce mice that lack functioning genes for aquaporins. How would the urine of these mice compare to that of mice with normal aquaporins?
a. Lower volume and lower osmolarity
b. Lower volume and higher osmolarity
c. Higher volume and lower osmolarity
d. Higher volume and higher osmolarity

Verified step by step guidance

1. Understand the role of aquaporins: Aquaporins are membrane proteins that facilitate the transport of water across cell membranes. They are crucial for maintaining water balance in cells and tissues.
2. Consider the effect of lacking aquaporins: Without functioning aquaporins, the ability of cells, particularly in the kidneys, to reabsorb water is impaired. This means that more water remains in the urine, leading to changes in urine volume and concentration.
3. Analyze urine volume: Mice lacking aquaporins would likely produce urine with a higher volume because less water is reabsorbed back into the body from the urine.
4. Analyze urine osmolarity: With less water reabsorption, the urine would be less concentrated, leading to lower osmolarity. Osmolarity refers to the concentration of solutes in the urine.
5. Combine the effects: Based on the analysis, the urine of mice lacking aquaporins would have a higher volume and lower osmolarity compared to mice with normal aquaporins.

Key Concepts

Aquaporins

Aquaporins are integral membrane proteins that serve as channels for water transport across cell membranes. They play a crucial role in maintaining water homeostasis in organisms by facilitating rapid and selective water movement. In the kidneys, aquaporins are essential for concentrating urine and regulating its volume and osmolarity.

Urine Osmolarity

Urine osmolarity refers to the concentration of solutes in urine, which is a measure of its ability to concentrate or dilute. It is influenced by the kidney's ability to reabsorb water and solutes, a process heavily dependent on aquaporins. In the absence of functioning aquaporins, urine osmolarity is likely to be higher due to reduced water reabsorption.

Water Reabsorption in Kidneys

Water reabsorption in the kidneys is a critical process for maintaining body fluid balance and is primarily facilitated by aquaporins in the renal tubules. Without aquaporins, the kidneys cannot efficiently reabsorb water, leading to increased urine volume and altered osmolarity. This process is vital for understanding how genetic modifications affecting aquaporins impact urine characteristics.