The following organisms have structures for movement except

Analyze the question: We need the organism that does NOT have a structure for movement (locomotion). Three of the four have specialized structures, and one does not.

Explain the concept: Many simple organisms move using special structures:

• Pseudopodia ("false feet") are temporary extensions of the cytoplasm.
• Cilia are short, hair-like structures that beat in coordinated waves.
• Flagella are long, whip-like structures.

Step-by-step solution:

• A. Amoeba: Moves using pseudopodia. It has a structure for movement.
• B. Spirogyra: A filamentous green alga found in ponds and slow-moving freshwater. It has no cilia, flagella, or pseudopodia. It floats as long, slimy threads and does not actively move. It has no locomotory structure.
• C. Volvox: A colonial green alga. Each cell has two flagella, and the colony rolls through the water. It has a structure for movement.
• D. Paramecium: Covered in cilia, which it uses to swim. It has a structure for movement.

Answer: Spirogyra is the exception, so the correct option is B.

Tip: Match each organism to its locomotory structure:

• Amoeba → pseudopodia
• Paramecium → cilia
• Volvox, Euglena → flagella
• Spirogyra → none (filamentous and non-motile)

When you see "except" in a question, find the three that fit the pattern and pick the odd one out.