Holozoic nutrition in protozoa — which statement correctly defines this feeding mode?

Difficulty: Easy

Correct Answer: Phagocytosis of solid nutrients followed by formation of phagocytic (food) vacuoles

Explanation:

Introduction:Holozoic nutrition describes animal-like feeding. Protozoa with this habit ingest particulate food and digest it intracellularly, analogous to macrophage phagocytosis.

Given Data / Assumptions:

  • We must focus on solid vs soluble food and the uptake mechanism.
  • Food vacuole formation is central to intracellular digestion.

Concept / Approach:Holozoic = ingestion of solid particles. Pinocytosis takes up fluids/solutes; photosynthesis is autotrophic, not holozoic. Therefore the accurate description centers on phagocytosis of solids and food vacuole formation.

Step-by-Step Solution:

Identify holozoic hallmark: phagocytosis of solid prey ✔Confirm subsequent digestion occurs in food vacuoles ✔Exclude pinocytosis (fluids) ✘Exclude photosynthesis (autotrophy) ✘

Verification / Alternative check:Classic amoebae feed by engulfing bacteria/algae fragments and digesting them in vacuoles; microscopy confirms stepwise phagosome to phagolysosome maturation.

Why Other Options Are Wrong:

  • Pinocytosis of solids: solids are not pinocytosed; pinocytosis targets fluids.
  • Phagocytosis of soluble nutrients: “soluble” contradicts phagocytosis.
  • Photosynthesis: not a feeding mode of holozoic protozoa.

Common Pitfalls:Confusing pinocytosis with phagocytosis; assuming any vacuole equals food vacuole.

Final Answer:Phagocytosis of solid nutrients followed by formation of phagocytic (food) vacuoles

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