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Homeostasis is the maintenance of a stable internal environment (A-level only)

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Question 4

The loop of Henle is a specialized structure in the nephrons of mammalian kidneys that is essential for water conservation.

a.

Explain how a longer loop of Henle in the desert hopping mouse (Notomys alexis) enables it to survive in extremely arid conditions with very limited access to drinking water.

[2]
b.

Ecophysiologists studying water-conservation adaptations in arid-zone mammals model the relationship between the maximum urine concentration, UUU (in mOsmol kg−1\text{mOsmol kg}^{-1}mOsmol kg−1), and the relative medullary thickness, MMM, using the equation:

U=380(M−0.4)+372 U = 380(M - 0.4) + 372 U=380(M−0.4)+372

Calculate the relative medullary thickness of a species of hopping mouse that produces a maximum urine concentration of 3830 mOsmol kg−13830\text{ mOsmol kg}^{-1}3830 mOsmol kg−1. Show your working.

[2]

Homeostasis is the maintenance of a stable internal environment (A-level only) Questions

  1. A Level
  2. /Biology
  3. /Homeostasis is the maintenance of a stable internal environment (A-level only)