If a cell has a diploid number of 50, how many chromosomes are present in the nucleus at the beginning of meiosis? how many chromosomes are present in each resulting nucleus at the end of meiosis?

Beginning of meiosis: 50 chromosomes

Chromosomes in each of the nucleus formed by meiosis: 25

Explanation:

Meiosis is a reduction division as it has two successive divisions without any intervening S-phase. It forms a total of four daughter nuclei each having half the chromosome number as present in the parent cell at the beginning of the process.

If a cell with 2n=50 enters meiosis, the segregation of homologous chromosomes to the opposite poles during anaphase-I of meiosis I would result in the reduction of chromosome number to the half in each of the two daughter nuclei formed by the end of the meiosis-I.

Meiosis-II is just like mitosis and maintains the chromosome number. So, the two daughter nuclei enter the meiosis-II and form a total of 4 daughter nuclei each of which has 25 chromosomes.