If the size of a fertilized egg of frog is compared with the size of its blastula and gastrula stages, which of the following observations will be correct?

Options

A. There is a progressive increase in size from zygote to blastula.
B. All the three will be of the same size
C. Zygote will be smaller, while blastula and gastrula will be larger
D. Gastrula will be larger white zygote and blastula will be of same size

Answer

To solve the question regarding the comparison of the sizes of a fertilized egg (zygote), blastula, and gastrula stages of a frog, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Stages**:
- The fertilized egg is referred to as the zygote.
- After fertilization, the zygote undergoes cleavage to form a blastula.
- The blastula then undergoes gastrulation to form the gastrula.

2. **Size Comparison**:
- The zygote (fertilized egg) and the blastula are typically similar in size. This is because the blastula is formed from the zygote through a series of cell divisions (cleavage) without significant growth in size.
- The gastrula, however, is larger than both the zygote and the blastula due to the processes of cell movement and differentiation that occur during gastrulation.

3. **Evaluating the Options**:
- **Option 1**: "There is a progressive increase in size from zygote to blastula." - This is incorrect because the zygote and blastula are approximately the same size.
- **Option 2**: "All three will be of the same size." - This is incorrect because the gastrula is larger than the zygote and blastula.
- **Option 3**: "Zygote will be smaller while blastula and gastrula will be larger." - This is incorrect because the zygote and blastula are similar in size.
- **Option 4**: "Gastrula will be larger while zygote and blastula will be of the same size." - This is correct as the gastrula is indeed larger than both the zygote and blastula.

4. **Conclusion**: The correct observation is that the gastrula is larger while the zygote and blastula are of the same size.

### Final Answer:
The correct observation is: **Gastrula will be larger while zygote and blastula will be of the same size.**

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