According to the SIBICO mnemonic, which statement is true?

• A. Sodium in, potassium out
• B. Magnesium in, calcium out
• C. Phosphate in, chloride out
• D. Sulfate in, bicarbonate out

Answer: (D)

SIBICO is used to memorize a specific pattern of ion movement across a membrane: sulfate moves into the cell while bicarbonate moves out. That directional pairing is what the mnemonic is built to remind you of, so the statement “sulfate in, bicarbonate out” fits the mnemonic exactly.

Think of it as a cue for an exchange-type transport where one ion enters the cell and the other exits it, a pattern that contrasts with other common transport ideas. For example, sodium moving into the cell while potassium moves out doesn’t follow this mnemonic’s pairing, and the other options describe ion movements that aren’t the pattern SIBICO emphasizes.