Question

What is the pairing of homologous chromosomes called?
(A) Disjunction
(B) Synapsis
(C) Segregation
(D) Polytene

Answer 1

Hint: In zygotene stage of prophase \[1\] of meiosis \[1\] does the pairing of homologous chromosomes starts and is amid the formation of a complex structure. A pair of paired homologous chromosomes forms a complex referred to as bivalent or tetrad. Also focus on the literal meanings of the choice to work out the incorrect answers from the correct one.

Complete answer:
Option A (Disjunction): In meiosis, disjunction happens when homologous chromosomes move apart toward the other poles of the cell in anaphase I. Disjunction again occurs when sister chromatids separate and move faraway from one another during anaphase II.
So, Option A isn't correct.
Option B (Synapsis): Synapsis is the pairing of two homologous chromosomes that happens during meiosis. This allows matching-up of homologous pairs before their segregation, and possible chromosomal crossover between them. The process of synapsis takes place during prophase I of meiosis.
So, Option B is correct.
Option C (Segregation): Chromosome segregation is that the process in eukaryotes by which two sister chromatids formed as a consequence of DNA replication, or paired homologous chromosomes, break away one another and migrate to opposite poles of the nucleus. This process of segregation occurs during both mitosis and meiosis.
So, Option C isn't correct.
Option D (Polytene): the Polytene chromosomes have \[1000\] times more DNA than the traditional somatic chromosomes. These chromosomes actually contain many strands, they're called Polytene chromosomes.
So, Option D isn't correct.

So, the correct answer is “Option B”.

Note:
Meiosis is a component of the sexual process because gametes (sperm, eggs) have one half the chromosomes as diploid (\[2\]N) individuals. There are two divisions in meiosis; the primary division is meiosis I: the amount of cells is doubled, but the amount of chromosomes isn't.This leads to $\dfrac{1}{2}$ as many chromosomes per cell.