In which group, the notochord is limited to only anterior part or probascis

Options

A. Hemichordata
B. Urochordata
C. Cephalochordata
D. Mammalia

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which group has a notochord that is limited to only the anterior part or proboscis.

2. **Identifying the Options**: The options provided are:
- Option 1: Hemichordata
- Option 2: Urochordata
- Option 3: Cephalochordata
- Option 4: Mammalia

3. **Analyzing Each Option**:
- **Hemichordata**: This group is characterized by having a notochord-like structure that is limited to the anterior part, known as the proboscis. This makes it a strong candidate for the answer.
- **Urochordata**: Members of this group, also known as tunicates, possess a notochord during their larval stage, but it is not limited to the anterior part. Hence, this option is incorrect.
- **Cephalochordata**: This group includes organisms like amphioxus, which have a notochord extending along the entire length of the body, not just the anterior part. Therefore, this option is also incorrect.
- **Mammalia**: Mammals have a complete notochord that is replaced by the vertebral column during development. This option is incorrect as well.

4. **Conclusion**: Based on the analysis, the correct answer is **Hemichordata** because it is the only group where the notochord is limited to the anterior part or proboscis.

5. **Final Answer**: The group in which the notochord is limited to only the anterior part or proboscis is **Hemichordata**.

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