What does fertilization restore in terms of chromosome number?

• A. Haploid number
• B. Diploid number
• C. Aneuploid number
• D. Polyploid number

Answer: (B)

Fertilization is the process where male and female gametes (sperm and egg) unite, leading to the formation of a zygote. Each gamete carries a haploid set of chromosomes, which means that they contain half the number of chromosomes found in the organism's somatic cells.

When these two haploid gametes fuse during fertilization, they combine their genetic material, effectively restoring the diploid chromosome number. This diploid state is characteristic of the fertilized egg (zygote) and is essential for the organism's development as it contains two sets of chromosomes—one from each parent.

The restoration of this diploid number is crucial for maintaining the species' chromosomal integrity across generations. This ensures that subsequent cell divisions (such as mitosis) and organismal development can occur correctly, preserving the species’ genetic information. Thus, the answer relating to the restoration of the diploid chromosome number after fertilization is indeed the correct choice.