Explanation: The zygotene chromosomes are more condensed than that in leptotene stage. The ball and seen mainly in leptotene stage while the O shaped structure is in diplotene. The thin chromatins are seen in interphase or pre-leptptene.

Explanation: The main process taking place in zygotene is synapsis i.e. lengthwise pairing of homologous chromosome. Recombination follows this pairing and occurs in the pachytene stage.

Explanation: In pro-terminal lengthwise pairing the pairing begins at the terminal and then it proceeds towards the centre. The reverse case is known as procentric.

Explanation: Mad2 is responsible for signalling improper binding of the spindle fiber to the centromere. This negative signal prevents apoptosis. Mdm2 is linked to p53 while Mcm activates ORC. Mek is a part of monomeric G protein signaling.

Explanation: Due to vibrations in the cytosol the chromosomes pair. This pairing is mainly due to hydrodynatic force. Another theory for pairing is via electrostatic force.

Explanation: Translocation may result in the chromosome that is partially homologous to two different chromosomes, this result in pairing of 4 chromosomes. Also homologous segments in non-homologous chromosomes can par. But pairing with more than 2 chromosomes in a normal instance is not seen.

Explanation: Unlike mitosis in meiosis there is both DNA synthesis and histone synthesis for protein compaction in meiosis stage. However, equatorial positioning is seen in metaphase only.

Explanation: Very less amount of DNA is replicated during zygotene while most are replicated in S phase. This unreplicated in DNA in chromosomes helps to hold the chromosomes together after zygotene.

Explanation: The amount of DNA left unreplicated is very less about 104 bp. Proper replication of this ensures zygotene progression.

Explanation: The carrying over of the phenomenon of DNA replication to the next stage of meiosis suggests that these sites are probably the locations where crossing over will occur.

Explanation: The replication of DNA in zygotene is mandatory for a synaptonemal complex formation to occur. These regions are also the first to get paired.

Explanation: DNA replicated in zygotene phase is not immediately incorporated in the chromosome but it takes 5-6 days. While zygotene is followed by pachytene and the synaptonemal complex is shorter than the chromosome itself. The pairing follows replication and not vice versa.