1) Explanation of Grades of Organization:
o Cellular grade organization: Found in simple multicellular organisms like sponges (e.g., Sycon), where cells perform basic functions without forming tissues.
o Protoplasmic grade organization: Observed in unicellular organisms like Paramecium, where a single cell performs all life functions.
o Cell-tissue grade organization: Seen in organisms like Jellyfish, where cells group to form tissues.
o Tissue-organ grade organization: Involves specialized tissues forming organs, typically in higher organisms like flatworms, not in sponges like Euplectella.
2) Why Option 4 is Incorrect:
o Euplectella (Venus flower basket) belongs to the phylum Porifera and exhibits cellular grade organization, not tissue-organ grade organization.
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