In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current source file to be included only once in a single compilation.
During sexual reproduction, fertilization of the ovum (n, 23 chromosomes) by the sperm (n, 23 chromosomes) restores the diploid number and creates a zygote (2n, 46) (awww..) that divides and grows by mitosis to form a multicellular human.
Summary: At the end of meiosis, 4 daughter cells are formed = eggs or sperm. Each contains half as many chromosomes as the parent cell (n); each cell is genetically different from its parents and from its siblings. Fertilization of an egg by a sperm restores the chromosome number to 2n. All cells in a higher eukaryote (like us) are diploid Â­ EXCEPT ...for the germ cells Â­ eggs and sperm. 2  Germ cells have only half the number of chromosomes as a diploid cell Â­ one of each pair-and are termed haploid (n) . 3  In a human egg or sperm, there are 23 chromosomes, one of which is an X or Y.