Which of the following statements is incorrect regarding organisms of phylum Chordata?

Options

A. The organism are characterized by the presence of a notochord and a ventral hollow nerve cord
B. They are triploblastic and bilaterally symmetrical
C. They have a ventral heart
D. They are further divided into three subphyla.

Answer

To solve the question regarding which statement is incorrect about organisms of phylum Chordata, we will evaluate each option provided.

### Step-by-Step Solution:

1. **Evaluate the First Statement**:
- The statement claims that organisms are characterized by the presence of a notochord and a ventral hollow nerve cord.
- **Analysis**: While it is true that chordates have a notochord, the nerve cord is not ventral; it is actually dorsal and hollow.
- **Conclusion**: This statement is incorrect.

2. **Evaluate the Second Statement**:
- The statement claims that chordates are triploblastic and bilaterally symmetrical.
- **Analysis**: Chordates do have three germ layers (ectoderm, mesoderm, endoderm), making them triploblastic. They are also bilaterally symmetrical, meaning their left and right sides are mirror images.
- **Conclusion**: This statement is correct.

3. **Evaluate the Third Statement**:
- The statement claims that chordates have a ventral heart.
- **Analysis**: In chordates, the heart is indeed located ventrally (below) the alimentary canal.
- **Conclusion**: This statement is correct.

4. **Evaluate the Fourth Statement**:
- The statement claims that chordates are further divided into three subphyla.
- **Analysis**: Chordates are classified into three subphyla: Urochordata, Cephalochordata, and Vertebrata.
- **Conclusion**: This statement is correct.

### Final Conclusion:
After evaluating all the statements, the first statement is the only incorrect one. Therefore, the answer to the question is that the first statement is incorrect regarding organisms of phylum Chordata.

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