Which of the following statement is correct?
1. In Urochordates like Ascidia, Salpa, Doliolum notochord is present in only larval tail.
2. In cephalochordates like Branchiostoma (Amphioxus or Lancelet) notochord extends from head to tail and is persistent throughout the life
3. All vertebrates are chordates but all chordates are not vertebrates
4.In vertebrates Notochord is replaced by vertebral column

Options

A. All are correct
B. Only II and IV are correct
C. All are wrong
D. Only Il is wrong

Answer

To determine which of the statements is correct, let's analyze each one step by step:

1. **Statement 1**: "In Urochordates like Ascidia, Salpa, Doliolum notochord is present in only larval tail."
- **Analysis**: In Urochordates, the notochord is indeed present only in the larval stage and specifically in the tail region. In adults, the notochord is absent. Therefore, this statement is **correct**.

2. **Statement 2**: "In cephalochordates like Branchiostoma (Amphioxus or Lancelet) notochord extends from head to tail and is persistent throughout the life."
- **Analysis**: In Cephalochordates, the notochord does extend from the head to the tail and remains throughout the organism's life. Thus, this statement is also **correct**.

3. **Statement 3**: "All vertebrates are chordates but all chordates are not vertebrates."
- **Analysis**: This statement is true. All vertebrates belong to the phylum Chordata, but there are many chordates (like Urochordates and Cephalochordates) that are not vertebrates. Hence, this statement is **correct**.

4. **Statement 4**: "In vertebrates, notochord is replaced by vertebral column."
- **Analysis**: This statement is also true. In vertebrates, the notochord is present during early development but is replaced by the vertebral column as the organism matures. Therefore, this statement is **correct**.

**Conclusion**: All four statements are correct based on the analysis above.