Which of the following is an example of a membranous organelle in eukaryotic cells?

• A. Mitochondrion
• B. Ribosome
• C. Nucleolus
• D. Centrosome

Answer: (A)

Verified step by step guidance

1. Understand the definition of a membranous organelle: Membranous organelles are structures within eukaryotic cells that are surrounded by lipid bilayer membranes, which separate their internal environment from the cytoplasm. Examples include the mitochondrion, endoplasmic reticulum, Golgi apparatus, and lysosomes.
2. Analyze the options provided: Mitochondrion, Ribosome, Nucleolus, and Centrosome. Determine which of these are surrounded by membranes.
3. Evaluate the mitochondrion: The mitochondrion is a double-membrane organelle, with an outer membrane and an inner membrane that encloses the matrix. It is a classic example of a membranous organelle.
4. Evaluate the ribosome: Ribosomes are not surrounded by membranes. They are composed of RNA and proteins and are involved in protein synthesis, but they are not membranous organelles.
5. Evaluate the nucleolus and centrosome: The nucleolus is a dense region within the nucleus where ribosomal RNA is synthesized, but it is not surrounded by a membrane. The centrosome is involved in organizing microtubules during cell division and is also not a membranous organelle.