Which of the following structures is surrounded by two phospholipid bilayers?

• A. Lysosome
• B. Golgi apparatus
• C. Ribosome
• D. Nucleus

Answer: (D)

Verified step by step guidance

1. Understand the structure of a phospholipid bilayer: A phospholipid bilayer consists of two layers of phospholipids, with hydrophilic (water-attracting) heads facing outward and hydrophobic (water-repelling) tails facing inward. This structure forms the basic framework of cell membranes.
2. Identify the organelles in the cell that are surrounded by membranes: In eukaryotic cells, organelles such as the nucleus, mitochondria, and chloroplasts are surrounded by membranes. Some organelles have a single membrane, while others have double membranes.
3. Recognize that the nucleus is surrounded by a double membrane: The nucleus is enclosed by the nuclear envelope, which consists of two phospholipid bilayers. This double membrane separates the contents of the nucleus from the cytoplasm and regulates the passage of molecules in and out of the nucleus.
4. Compare the membrane structures of the other options: Lysosomes and the Golgi apparatus are surrounded by a single phospholipid bilayer, while ribosomes are not surrounded by any membrane.
5. Conclude that the nucleus is the correct answer: Based on the information that the nucleus is surrounded by two phospholipid bilayers, it is the correct answer to the question.