EVOLUTION
SOURCES OF VARIATION IN A POPULATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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A chromosomal mutation is a change in the sequence nucleotide bases in single gene.
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Independent assortment occurs during Prophase I of Meiosis I.
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Crossing over occurs during Prophase I of Meiosis I.
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Gene mutation is altenations in the number or structure of chromosomes.
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Detailed explanation-1: -Crossing over occurs during prophase I of meiosis before tetrads are aligned along the equator in metaphase I. By meiosis II, only sister chromatids remain and homologous chromosomes have been moved to separate cells.
Detailed explanation-2: -Answer and Explanation: The correct option is d. during meiosis I only. The crossing over is an event that occurs during the prophase of the first meiotic division.
Detailed explanation-3: -Crossing over is an enzyme-mediated process, where the exchange of genetic material between non-sister chromatids of homologous chromosomes takes place. It occurs at the pachytene stage of prophase I of meiosis.
Detailed explanation-4: -So, the correct answer is Pachytene.
Detailed explanation-5: -Crossing-over occurs during prophase I, and it is the exchange of genetic material between non-sister chromatids of homologous chromosomes. Recall during prophase I, homologous chromosomes line up in pairs, gene-for-gene down their entire length, forming a configuration with four chromatids, known as a tetrad.