Which best describes the difference between protists that have cilia and those that have flagella?

• A. Cilia are found only in multicellular protists, while flagella are found only in unicellular protists.
• B. Protists with cilia can photosynthesize, while those with flagella cannot.
• C. Cilia are used only for feeding, while flagella are used only for movement.
• D. Cilia are short and numerous, moving the protist by coordinated beating, while flagella are longer and usually fewer in number, moving the protist with a whip-like motion.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the role of cilia and flagella in protists. Both are structures used for movement, but they differ in their physical characteristics and mechanisms of action.
2. Step 2: Learn about cilia. Cilia are short, hair-like structures that are numerous on the surface of the protist. They move in a coordinated, wave-like manner to propel the organism or to move substances along its surface.
3. Step 3: Learn about flagella. Flagella are longer, whip-like structures that are fewer in number (often one or two per protist). They move in a whip-like motion to propel the organism through its environment.
4. Step 4: Compare the two structures. Cilia are short and numerous, providing movement through coordinated beating, while flagella are longer and fewer, providing movement through a whip-like motion.
5. Step 5: Recognize that the correct answer highlights the physical and functional differences between cilia and flagella, emphasizing their distinct roles in protist movement.