Which of the following statements best describes microtubules?

• A. Microtubules are flexible structures that form the cell's outer membrane.
• B. Microtubules are hollow tubes that provide structural support and are involved in intracellular transport.
• C. Microtubules are composed of actin and are involved in cell motility.
• D. Microtubules are thin filaments primarily responsible for muscle contraction.

Answer: (B)

Verified step by step guidance

1. Understand the structure of microtubules: Microtubules are cylindrical structures made of tubulin proteins. They are not flexible structures forming the cell's outer membrane.
2. Recognize the function of microtubules: They provide structural support to the cell and are crucial for intracellular transport, helping move organelles and vesicles within the cell.
3. Differentiate microtubules from other cytoskeletal elements: Microtubules are distinct from actin filaments, which are involved in cell motility, and from thin filaments responsible for muscle contraction.
4. Identify the composition of microtubules: They are composed of tubulin, not actin, which is a key point in distinguishing them from other cytoskeletal components.
5. Conclude with the correct description: Microtubules are hollow tubes that provide structural support and are involved in intracellular transport, which aligns with the correct answer provided.