Which of the following statements correctly characterizes eukaryotic organelles?

• A. They exist outside the cell and help in cell-to-cell communication.
• B. They are specialized subunits within a cell, often surrounded by membranes, that perform distinct functions.
• C. They are only found in prokaryotic cells and lack any membrane-bound structure.
• D. They are composed entirely of DNA and are responsible for protein synthesis.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the definition of eukaryotic organelles. Eukaryotic organelles are specialized structures within eukaryotic cells that perform distinct functions. Many of these organelles are membrane-bound, meaning they are enclosed by lipid bilayers that separate their internal environment from the cytoplasm.
2. Step 2: Analyze the first statement: 'They exist outside the cell and help in cell-to-cell communication.' This is incorrect because organelles are located inside the cell, not outside. Cell-to-cell communication is typically facilitated by signaling molecules, not organelles.
3. Step 3: Analyze the second statement: 'They are specialized subunits within a cell, often surrounded by membranes, that perform distinct functions.' This is correct because it accurately describes the nature of eukaryotic organelles, such as the nucleus, mitochondria, and endoplasmic reticulum.
4. Step 4: Analyze the third statement: 'They are only found in prokaryotic cells and lack any membrane-bound structure.' This is incorrect because organelles are characteristic of eukaryotic cells, not prokaryotic cells. Prokaryotic cells lack membrane-bound organelles.
5. Step 5: Analyze the fourth statement: 'They are composed entirely of DNA and are responsible for protein synthesis.' This is incorrect because organelles are not composed entirely of DNA. While the nucleus contains DNA and ribosomes are involved in protein synthesis, organelles like mitochondria and the Golgi apparatus have other functions unrelated to DNA.