[Campbell Biology P.1054] If a mutation prevented the mammary gland cells from responding to ... | Practice Question

If a mutation prevented the mammary gland cells from responding to oxytocin during nursing, what would be the most likely consequence for the milk release pathway, based on the described feedback mechanism?

  • A: Milk release would significantly increase due to compensatory mechanisms.
  • B: The suckling stimulus would be amplified, leading to excessive oxytocin production but no milk release.
  • C: The positive feedback loop would be disrupted, leading to a diminished or absent milk release despite continued suckling.
  • D: The pathway would switch to a negative feedback loop to maintain milk volume.

Explanation

The oxytocin pathway is a positive feedback loop, meaning the response milk release amplifies the initial stimulus suckling . If mammary gland cells cannot respond to oxytocin, milk release will not occur. Without milk release, the amplification effect of the positive feedback loop is broken, meaning the continued suckling stimulus will not lead to the increased milk production characteristic of a functioning positive feedback system.