Because of the fission process that consumes the fuels, the old fuel rods must be changed periodically to fresh ones (this period is called a cycle). However, only a part of the assemblies (typically one-third) are removed since the fuel depletion is not spatially uniform.
In fertilization, the sperm and egg both contain one set of chromosomes. the father (sperm) and one from the mother (egg). In SCNT, the egg cell's single set of chromosomes is removed. chromosomes. come from the somatic cell.
The sperm is the main reproductive cell in males. The sperms differ in that each carry a set of chromosomes dividing each into either a male, or female sperm. The females differ in that they carry a X gene, while the male sperm carry a Y gene.