Which of the following structures is responsible for enclosing the contents of a typical animal cell?

• A. Golgi apparatus
• B. Nucleus
• C. Mitochondrion
• D. Plasma membrane

Answer: (D)

Verified step by step guidance

1. Understand the question: The problem asks which structure encloses the contents of a typical animal cell. This means identifying the structure that forms the boundary of the cell and separates its internal environment from the external environment.
2. Review the function of each option: The Golgi apparatus is involved in modifying, sorting, and packaging proteins and lipids for secretion or use within the cell. The nucleus houses the cell's genetic material and controls cellular activities. The mitochondrion is the powerhouse of the cell, responsible for energy production. The plasma membrane, however, is the structure that surrounds the cell and acts as a selective barrier.
3. Recall the definition of the plasma membrane: The plasma membrane is a phospholipid bilayer embedded with proteins, carbohydrates, and cholesterol. It regulates the movement of substances in and out of the cell, maintaining homeostasis.
4. Eliminate incorrect options: Since the Golgi apparatus, nucleus, and mitochondrion are internal organelles and do not form the outer boundary of the cell, they cannot be the correct answer. The plasma membrane is the only structure that encloses the entire cell.
5. Conclude: Based on the above analysis, the plasma membrane is responsible for enclosing the contents of a typical animal cell and maintaining its integrity.