Individuals with an inherited autosomal recessive disorder called primary ciliary dyskinesia (PCD) often have severe respiratory problems due to defective cilia. Males with PCD are often sterile because they produce sperm with defective flagella. Which of the following most likely explains the effect of the recessive allele?
(A) The mitochondria are defective and do not produce sufficient protein to synthesize microtubules in the cilia and flagella.
(B) The plasma membrane of the alveoli is not permeable to carbon dioxide during respiration because it is too hydrophobic.
(C) The Golgi bodies secrete an enzyme that destroys the proteins in the flagella and cilia.
(D) The cells do not produce functional motor proteins in flagella and cilia.
Ans: (D) The cells do not produce functional motor proteins in flagella and cilia.
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