A gradual decrease in size of tail during metamorphosis of frog is due to

Options

A. Cell necrosis
B. Pinocytic activity
C. Programmed cell death
D. Cell senescence

Answer

To answer the question regarding the gradual decrease in size of the tail during the metamorphosis of a frog, we can analyze the options provided step by step.

### Step-by-Step Solution:

1. **Understanding Metamorphosis**:
- Metamorphosis in frogs is a biological process where the frog undergoes significant physical changes from a tadpole to an adult frog. One of the notable changes is the gradual reduction of the tail.

2. **Analyzing the Options**:
- **Option 1: Cell Necrosis**:
- Cell necrosis refers to the premature death of cells due to injury or damage. This process does not specifically account for the gradual and controlled reduction of the tail size during metamorphosis. Therefore, this option is incorrect.

- **Option 2: Spinocytic Activity**:
- Spinocytic activity is a form of endocytosis where small particles are engulfed by the cell. This process is not related to the reduction of tail size in frogs. Hence, this option is also incorrect.

- **Option 3: Programmed Cell Death (Apoptosis)**:
- Programmed cell death, or apoptosis, is a regulated process where cells undergo an orderly death as part of normal development. During metamorphosis, the cells in the tail are programmed to die, leading to the gradual decrease in tail size. This makes this option the correct answer.

- **Option 4: Cell Senescence**:
- Cell senescence refers to the process where normal cells cease to divide and enter a state of permanent growth arrest. This does not specifically explain the gradual decrease in tail size during metamorphosis, making this option incorrect as well.

3. **Conclusion**:
- The correct answer to the question is **Option 3: Programmed Cell Death**. This process is responsible for the gradual reduction in the size of the tail during the metamorphosis of a frog.