In a typical angiosperm, if the chromosome number in the endosperm is 72 , what will be the chromosome number in its synergid cell and secondary nucleus, respectively?

Step-by-step solution

The endosperm of a typical angiosperm is a triploid ( 3n ) tissue formed by triple fusion. Given the endosperm chromosome number is 72 , we have 3n = 72 , which means the haploid chromosome number is n = 24 . The synergid is a cell of the female gametophyte (embryo sac) and is haploid ( n ). Therefore, its chromosome number is 24 . The secondary nucleus is formed by the fusion of two haploid polar nuclei in the central cell before fertilization, making it diploid ( 2n ). Therefore, its chromosome number is 2 24 = 4