Question

The pairing of homologous chromosomes takes place in ……………… phase.
A. Anaphase I
B. Prophase I
C. Anaphase II
D. Prophase II
E. Metaphase I

Answer 1

A couple of homologous chromosomes which are also known as homologs are a combination of one maternal and one paternal chromosome. These chromosomes are paired up with each other inside a cell at the time of fertilization. Homologs contain the same genes in the same loci. The pairing of homologous chromosomes is known as synapsis.

Complete answer:
Meiosis is a process of two cell divisions that produce four haploid daughter cells and each cell contains half the number of chromosomes as the parent cell. The number of chromosomes in a germ cell reduces by half by first separating the homologous chromosomes in meiosis I and then the sister chromatids in meiosis II. Meiosis I have four stages which are Prophase I, Metaphase I, Anaphase I, and Telophase I. And the meiosis II also has four stages; Prophase II, Metaphase II, Anaphase II, and Telophase II.
In prophase I, the chromosome is aligned with its homologous partner. Prophase I is further classified into four stages which are Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis. During the zygotene, the homologous chromosomes are pairing up with each other by a synapsis process.
In metaphase I, the pairs of homologous chromosomes are lining up in a random order along with the metaphase plate.
In anaphase I, the homologous chromosomes are separated from each other and segregated into two daughter cells which enter into the meiosis II phase.
During prophase II, the chromatids become shorter and thicker and Chromosomes get condense and centrosomes steps to the opposite sides of the cell.
During anaphase II, the spindle fibres are separated from non-sister chromatids, and the separated chromatids steps to the opposite ends of the cell.

Therefore, the correct option is option B.

Additional information:
Chromosomes are a linear combination of deoxyribonucleic acid and histone proteins, which build a complex structure called chromatin. Homologous chromosomes are composed of chromosome pairs where both have the same length, centromere position, and staining pattern. They also possess the same genes with the same corresponding loci. One homologous chromosome comes from the organism's mother and the other comes from the organism's father.

Note: A set of one maternal and one paternal chromosome whose genes are the same is called homologous chromosomes. These chromosomes are the same in length. Their position of centromere and pattern of staining is also the same. During the prophase I phase of meiosis I, these chromosomes are pairing up with each other by a synapsis process.