Question

which characteristic distinguishes muscle cells from most other human body cells? muscle cells are circular in shape. muscle cells are all the same size. muscle cells work only when needed. muscle cells have multiple nuclei.

Explanation:

• Analyze the first option: Most muscle cells (like skeletal and cardiac) are not circular; e.g., skeletal muscle cells are long and cylindrical, so this is incorrect.
• Analyze the second option: Muscle cells vary in size; different muscle types and even within a type, sizes can differ, so this is wrong.
• Analyze the third option: Many body cells work on demand (e.g., immune cells), so this isn't unique to muscle cells.
• Analyze the fourth option: Skeletal muscle cells (a major muscle cell type) are multinucleated, while most human body cells are mononucleated. This is a key distinguishing feature.

Answer:

D. Muscle cells have multiple nuclei