Which of the following statements is true for cytosol but not for cytoplasm?

• A. It includes the contents of the endoplasmic reticulum.
• B. It contains the nucleus and all organelles.
• C. It is synonymous with the entire cell interior.
• D. It excludes all membrane-bound organelles.

Answer: (D)

Verified step by step guidance

1. Understand the difference between cytosol and cytoplasm: Cytoplasm refers to the entire contents of the cell within the plasma membrane, excluding the nucleus, and includes organelles, cytosol, and other structures. Cytosol, on the other hand, is the fluid portion of the cytoplasm that excludes all membrane-bound organelles.
2. Analyze the first statement: 'It includes the contents of the endoplasmic reticulum.' This is incorrect for cytosol because the endoplasmic reticulum is a membrane-bound organelle, and cytosol excludes all such organelles.
3. Analyze the second statement: 'It contains the nucleus and all organelles.' This is incorrect for cytosol because the nucleus and organelles are not part of the cytosol; they are part of the cytoplasm.
4. Analyze the third statement: 'It is synonymous with the entire cell interior.' This is incorrect for cytosol because the entire cell interior includes organelles, the nucleus, and other structures, which are not part of the cytosol.
5. Analyze the fourth statement: 'It excludes all membrane-bound organelles.' This is correct for cytosol because, by definition, cytosol is the fluid portion of the cytoplasm that excludes all membrane-bound organelles.