Final answer:
The statement that cells are haploid after the completion of meiosis I is true. During meiosis I, homologous chromosomes are separated, and after meiosis II, sister chromatids separate to form four unique haploid daughter cells.
Step-by-step explanation:
True or False: Once meiosis I is completed, cells are haploid. The statement is true. After the completion of meiosis I, the cells are indeed haploid. This is because during meiosis I, homologous chromosomes are separated into two new cells, leaving each cell with only one set of chromosomes, which is the definition of a haploid cell. Even though each chromosome still consists of two sister chromatids, the cell is considered haploid because it contains only one complete set of chromosomes. In the subsequent phase, meiosis II, these sister chromatids will separate, resulting in four haploid daughter cells that are genetically unique.