Which of the following is true w.r.t. cnidoblast?
These oval shaped cells are abundant on tentacles than body surface
cnidocyte is a part of cnidoblast which is filled with a poisonous fluid
once nematoblast is used, it migrates to gastrovascular cavity and digested
Nucleus is present in the centre of cell

Options

A. (A) only
B. (A) and (B)
C. (A) and ©
D. (B) ,© and (D)

Answer

To solve the question regarding cnidoblast, we need to evaluate each of the provided statements one by one:

1. **Statement 1**: "These oval shaped cells are abundant on tentacles than body surface."
- **Analysis**: Cnidoblasts, also known as cnidocytes, are indeed more abundant on the tentacles of cnidarians (like jellyfish and sea anemones) than on the body surface. They play a crucial role in defense and capturing prey.
- **Conclusion**: This statement is **true**.

2. **Statement 2**: "Cnidocyte is a part of cnidoblast which is filled with a poisonous fluid."
- **Analysis**: Cnidocytes contain specialized structures called nematocysts, which are filled with a stinging or poisonous fluid. The term "cnidocyte" refers to the entire cell, while "nematocyst" refers specifically to the stinging organelle within it.
- **Conclusion**: This statement is **true**.

3. **Statement 3**: "Once nematoblast is used, it migrates to gastrovascular cavity and digested."
- **Analysis**: This statement is incorrect. When a nematocyst (the stinging organelle) is discharged, it does not migrate to the gastrovascular cavity for digestion. Instead, it is simply used for defense or capturing prey, and the cnidocyte remains in place.
- **Conclusion**: This statement is **false**.

4. **Statement 4**: "Nucleus is present in the centre of cell."
- **Analysis**: This statement is also incorrect. The nucleus of a cnidocyte (or cnidoblast) is located at the basal end of the cell, not in the center.
- **Conclusion**: This statement is **false**.

**Final Conclusion**: The first and second statements are true, while the third and fourth statements are false. Therefore, the correct answer is that the first and second statements are true regarding cnidoblasts.