What is notochord?

Options

A. aaBB`xx`aaBB
B. AABB`xx`aabb
C. AaBb`xx`AaBb
D. AABB

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks about the notochord, which is a significant structure in embryonic development.

2. **Definition of Notochord**: The notochord is a flexible rod-like structure that is found in the embryos of all chordates. It serves as a primary skeletal element during the early stages of development.

3. **Function of Notochord**: The notochord provides structural support and defines the body axis. It plays a crucial role in the development of the vertebral column (spine) and is involved in signaling processes that influence the development of surrounding tissues.

4. **Presence in Different Organisms**: In vertebrates, the notochord is present during embryonic development but is typically replaced by the vertebral column in adults. In some invertebrates, the notochord persists throughout life.

5. **Significance in Evolution**: The notochord is a defining characteristic of the phylum Chordata, which includes all vertebrates and some invertebrates. It is an important evolutionary feature that indicates a common ancestry among chordates.

6. **Conclusion**: In summary, the notochord is a vital embryonic structure that provides support and plays a key role in the development of the vertebrate body plan.

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