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Which stage is responsible for genetic variation and evolution of species?
A. Diplotene
B. Diakinesis
C. Pachytene
D. Anaphase II

Last updated date: 22nd Feb 2024
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IVSAT 2024
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Hint: Genetic variation applies to genetic frequency diversity. Genetic variation may apply to differences between people or even to differences among populations. Mutated genes seem to be the actual cause of genetic modification. Evolution is based on the concept that all species are linked and progressively change with time. Evolution focuses on genetic diversity In a population that impacts the phenotype of a species.

Complete answer: If the genetic variation and species evolution have to take place, then there should be dealings of genetic material between them. This occurs in the pachytene stage of meiosis. Meiosis is the third stage of prophase in the meiotic division, in which each set of chromosomes splits into daughter chromosomes with gene breakage and crossing over of genetic material. Points whereby homologous crossover and exchange genetic material are chosen almost randomly and will be specific for each cell that goes through meiosis. If meiosis happens multiple times, as in humans, crossovers will appear at so many different points.
So, the correct answer is (C).
Additional Information:
During the phase of diplotene, the two homologous pairs begin to move apart as the synaptonemal complex unravels between two chromosomal arms and starts to resist each other. This makes the two chromosomes shift apart, held only by chiasma. Diakinesis is the final stage of Prophase-I and also the end of the condensation of chromosomes that enables the chiasmata and bivalent framework to be seen quite clearly under electron microscopy. During diakinesis, chromosomes are one of their most compact packages.

Note: Prophase I, meiosis is the very first stage of meiosis and has been represented by five discrete stages: Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis. Prophase 1 is effectively a crossover and recombination of genetic material between non-sister chromatids, culminating in genetically unknown, haploid, daughter chromatic cells.