Question

All of the following are true about phagocytosis EXCEPT:

• A. Amoeba and other protozoans live their life by it
• B. Used to ingest particles < 0.5 microns in size
• C. Used to ingest particles > 0.5 microns in size
• D. Digestion occurs within phagolysosomes

Hint:

Sub-half-micron uptake belongs to pinocytosis, not phagocytosis.

Answer 1

The Correct Option is B

This is an "except" question, so identify the one statement that does not fit phagocytosis. The defining size rule is the easiest discriminator: phagocytosis is reserved for large material, conventionally taken as larger than roughly 0.5 micron, which includes whole bacteria, apoptotic cells, and particulate debris. Anything below that threshold, and especially extracellular fluid, is taken up by pinocytosis instead. Now scan each choice. Free-living protozoa such as amoebae genuinely survive by phagocytosing food particles, so that statement holds. The claim that phagocytosis ingests particles above 0.5 micron also holds, since that is its job. The final option correctly describes the fate of the ingested material: the phagosome fuses with lysosomes to create a phagolysosome, the acidic compartment in which enzymatic digestion takes place. That leaves the statement assigning sub-0.5-micron uptake to phagocytosis as the wrong one.

\[\boxed{\text{Used to ingest particles} < 0.5 \text{ microns}}\]