In the Research on Na⁺ Uptake by Clam Cells,the Researchers

question 3

Multiple Choice

In the research on Na⁺ uptake by clam cells,the researchers focused on Na⁺ transporters.Why can't Na⁺ ions cross a cell membrane without a transport protein?

• A) There is not a Na⁺ gradient without a transport protein.
• B) Na⁺ is hydrophobic.
• C) Na⁺ uptake requires active transport.
• D) Na⁺ can diffuse directly across a membrane.
• E) Membranes are hydrophobic.

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