試題詳解

15. Why do cells not have membrane transport proteins for O2?
(A) Because oxygen can dissolve in the lipid bilayer and diffuse in and out rapidly without the need for a transporter.
(B) Because oxygen can dissolve in water and leak in via water channels.
(C) Because they need to keep the oxygen concentration low inside the reducing environment of the cell.
(D) Because oxygen transport across a membrane is energetically unfavorable.
(E) Because oxygen is transported in and out of the cell in special oxygen-carrying proteins such as hemoglobin.