Which of the following are triploblastic, acoelomate with blind sac type of body plan, and parechyma cells originating from mesoderm fill up the cavities of the body ?

Options

A. Cnidarians
B. Plathyhelminthes
C. Annelids
D. Arthropoda

Answer

To solve the question regarding which organisms are triploblastic, acoelomate with a blind sac type of body plan, and have parenchyma cells originating from the mesoderm, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terms**:
- **Triploblastic**: Organisms that have three germ layers: ectoderm, mesoderm, and endoderm.
- **Acoelomate**: Organisms that do not have a body cavity (coelom).
- **Blind Sac Body Plan**: Organisms that have a single opening that serves as both mouth and anus.
- **Parenchyma Cells**: Cells that fill the body cavity, originating from the mesoderm.

2. **Identify Organism Groups**:
- **Porifera (sponges)**: These organisms are not triploblastic; they are considered parazoans.
- **Cnidaria (jellyfish, corals)**: These organisms are diploblastic (not triploblastic) and have a simple body plan with a single opening.
- **Platyhelminthes (flatworms)**: These organisms are triploblastic, acoelomate, have a blind sac body plan, and contain parenchyma cells originating from the mesoderm.
- **Annelida (segmented worms)**: These organisms are triploblastic but are coelomates (they have a body cavity).
- **Arthropoda (insects, arachnids)**: These organisms are also triploblastic and coelomate, not acoelomate.

3. **Evaluate Each Group**:
- **Porifera**: Not triploblastic → Incorrect.
- **Cnidaria**: Not triploblastic → Incorrect.
- **Platyhelminthes**: Triploblastic, acoelomate, blind sac body plan, and have parenchyma cells → Correct.
- **Annelida**: Triploblastic but coelomate → Incorrect.
- **Arthropoda**: Triploblastic but coelomate → Incorrect.

4. **Conclusion**:
- The only group that meets all the criteria of being triploblastic, acoelomate, having a blind sac body plan, and containing mesodermal parenchyma cells is **Platyhelminthes**.

### Final Answer:
The correct answer is **Platyhelminthes**.

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