Which components support the cytoplasm and help move substances and organelles within the cytoplasm?

• A. Microfilaments and microtubules
• B. Microvilli
• C. Centrioles
• D. Ribosomes

Answer: (A)

Movement of substances and organelles inside the cytoplasm relies on the cytoskeleton, especially microfilaments and microtubules. Microfilaments, made of actin, form a dynamic network just beneath the cell membrane that helps maintain shape and enables contractile movements, supporting intracytoplasmic flow and short-range transport. Microtubules are long, hollow tubes that act as tracks for motor proteins like kinesin and dynein, carrying vesicles, mitochondria, and other organelles to their proper locations and organizing their distribution throughout the cell. Centrioles assist in organizing the microtubule network, particularly during cell division, but they aren’t the direct rails for intracellular movement. Microvilli, on the other hand, increase surface area for absorption and don’t move substances inside the cytoplasm. Ribosomes synthesize proteins, not structural support or transport within the cytoplasm.