Chromosomes pair can align at metaphase plates in metaphase 1 , not in anaphase 1 . because homologous chromosomes have sapreted in anaphase 1 on the both side of poles.

Metaphase vs Anaphase in Meiosis I:

In order to understand why the alignment of chromosome pairs during anaphase of meiosis I is not considered metaphase, it is important to first comprehend the process of meiosis and the key events that occur during each phase.

Meiosis:
Meiosis is a type of cell division that occurs in sexually reproducing organisms, leading to the formation of gametes (eggs and sperm). It involves two rounds of cell division (meiosis I and meiosis II) and results in the formation of four genetically unique haploid daughter cells.

Meiosis I:
Meiosis I is the first division of meiosis, during which homologous chromosome pairs separate, resulting in the reduction of the chromosome number by half. It consists of four distinct phases: prophase I, metaphase I, anaphase I, and telophase I.

Metaphase I:
During metaphase I, the homologous chromosome pairs align along the metaphase plate, which is an imaginary plane equidistant from the two poles of the cell. The alignment occurs in a random manner, known as independent assortment, resulting in different combinations of chromosomes in the daughter cells. This process contributes to genetic diversity.

Anaphase I:
Anaphase I follows metaphase I and is characterized by the separation of homologous chromosome pairs. The homologous chromosomes, consisting of sister chromatids, are pulled apart and move towards opposite poles of the cell. Importantly, during anaphase I, the two chromosome pairs can align at the metaphase plate independently of each other.

Explanation:
The reason why the alignment of chromosome pairs during anaphase of meiosis I is not considered metaphase is because the chromosomes are no longer in their paired form. In anaphase I, the homologous chromosomes separate and move towards opposite poles of the cell, which means that each chromosome (consisting of two sister chromatids) is now considered an individual entity.

During metaphase I, the homologous chromosomes align at the metaphase plate as pairs, allowing for independent assortment and recombination. However, in anaphase I, the separation of these homologous chromosomes occurs, and they are no longer considered pairs. Each chromosome is now pulled towards the poles independently, contributing to the genetic diversity of the resulting daughter cells.

Therefore, while the alignment of chromosome pairs in metaphase I is a crucial step for the subsequent separation in anaphase I, the two chromosome pairs aligning independently at the metaphase plate during anaphase I signifies the separation of homologous chromosomes and the progression of meiosis I.