Which one of the following terms applies to the phylum Cnidaria?

• A. Radial symmetry
• B. Choanocytes
• C. Triploblastic
• D. Segmented body

Answer: (A)

Verified step by step guidance

1. Understand the key characteristics of the phylum Cnidaria. Cnidarians are aquatic animals that include jellyfish, corals, and sea anemones. They are known for their simple body structure and unique features like stinging cells (cnidocytes).
2. Review the concept of radial symmetry. Radial symmetry means that the body can be divided into similar halves by multiple planes passing through the central axis. This is a defining feature of Cnidarians, as their body structure is organized around a central axis.
3. Examine the term 'Choanocytes.' Choanocytes are specialized cells found in sponges (phylum Porifera), not Cnidarians. These cells are involved in water filtration and nutrient capture, so this term does not apply to Cnidaria.
4. Analyze the term 'Triploblastic.' Triploblastic organisms have three germ layers: ectoderm, mesoderm, and endoderm. Cnidarians are diploblastic, meaning they only have two germ layers (ectoderm and endoderm). Therefore, this term does not apply to Cnidaria.
5. Consider the term 'Segmented body.' Segmentation refers to the division of the body into repeated sections, as seen in annelids and arthropods. Cnidarians do not have a segmented body, so this term is also not applicable. The correct term that applies to Cnidaria is 'Radial symmetry.'