Photo AI
Describe how ultrafiltration occurs in a glomerulus - AQA - A-Level Biology - Question 1 - 2019 - Paper 3
Question 1
Describe how ultrafiltration occurs in a glomerulus. High blood hydrostatic pressure forces water and small solutes, such as glucose and ions, out of the blood in t... show full transcript
Worked Solution & Example Answer:Describe how ultrafiltration occurs in a glomerulus - AQA - A-Level Biology - Question 1 - 2019 - Paper 3
Step 1
Describe how ultrafiltration occurs in a glomerulus.
Answer
Ultrafiltration in a glomerulus occurs due to high blood hydrostatic pressure that forces water and small solutes, such as glucose, ions, and urea, through the capillary walls. The process involves the following key structures:
- Podocytes: Specialized cells with foot-like projections that create gaps for filtration.
- Endothelial cells: These cells have pores that allow small substances to pass while larger molecules, like proteins, are filtered out.
- Basement membrane: Acts as a final barrier to filter out larger proteins and retains blood cells.
Overall, the composition of the filtrate is primarily water, glucose, and ions, while larger blood components remain in circulation.
Step 2
Step 3
The equation shows the relationship between urine concentration in arbitrary units (y) and mean length of the loop of Henle in mm (x). Calculate the mean length of the loop of Henle in an organism that produces urine with a concentration of 16.56 arbitrary units.
Answer
To find the length of the loop of Henle, we can rearrange the equation
y = 0.72x + 4
Substituting y with 16.56:
Subtracting 4 from both sides:
Now, divide by 0.72:
Thus, the mean length of the loop of Henle is approximately 17.44 mm.
Step 4
Explain the pattern shown by the results in Figure 1.
Answer
The results in Figure 1 show a clear correlation between the thickness of the medulla and the concentration of urine produced. As the thickness of the medulla increases, the concentration of urine also increases. This suggests that a thicker medulla allows for a greater concentration of solutes due to a more efficient reabsorption process. This adaptation likely enables mammals to conserve water more effectively in environments where water availability is limited. Consequently, the evolution of thicker medullas could be an important factor in survival strategies across different species.