Which of the following statements accurately explains the purpose and mechanism of a physiological adaptation involving nutrient or gas exchange between a pregnant human mother and the fetus?

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The junction between maternal and fetal portions of the placenta offers a limited surface area so that blood flow from the mother is channeled directly to the fetus.

Fetal hemoglobin has a higher affinity for O2 than does maternal hemoglobin, which allows the fetus to always gain oxygen from the mother.

Blood flow in maternal and fetal arteries in the placenta runs countercurrent to allow for better nutrient exchange between vessels.

Villi within the placenta selectively block toxins that might otherwise cross into the fetal bloodstream.

 

asked Jan 1, 2013 in Biology by anonymous
    

1 Answer

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Fetal hemoglobin has a higher affinity for O2 than does maternal hemoglobin, which allows the fetus to always gain oxygen from the mother.

 

answered Jan 1, 2013 by anonymous



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