Which of the following processes results in a change of the cellular amount of DNA ?

Options

A. Blastulation
B. Fertilization
C. Cytokinesis
D. Spore formation

Answer

To determine which process results in a change of the cellular amount of DNA, we need to analyze each of the given options: blastulation, fertilization, cytokinesis, and spore formation.

### Step-by-Step Solution:

1. **Understand the Processes**:
- **Blastulation**: This is the process that occurs after fertilization where the zygote develops into a blastula. It does not change the amount of DNA in the cells; rather, it involves cell division without changing the overall DNA content.
- **Fertilization**: This is the fusion of two gametes (sperm and ovum) to form a zygote. Each gamete contains half the number of chromosomes (haploid), and when they fuse, they create a diploid zygote. This results in a doubling of the cellular amount of DNA.
- **Cytokinesis**: This is the process where the cytoplasm of a parental cell divides into two daughter cells after mitosis or meiosis. While it involves cell division, it does not change the total amount of DNA in the cells; it simply distributes the existing DNA into two new cells.
- **Spore Formation**: This is a form of asexual reproduction that produces spores. The amount of DNA remains the same as it is a process of replication without a change in ploidy level.

2. **Identify the Correct Process**:
- Among the options, **fertilization** is the only process that results in a change in the cellular amount of DNA. When the sperm and ovum fuse, the resulting zygote has a complete set of chromosomes (diploid), effectively doubling the DNA content compared to the haploid gametes.

3. **Conclusion**:
- Therefore, the correct answer to the question is **fertilization**.

### Final Answer:
The process that results in a change of the cellular amount of DNA is **fertilization**.