genetic_variation_in

Question 1 of 10

Animation Assessment

Question

What are the two processes in meiosis that create genetic differences among cells?

having two rounds of cell division and independent assortment

crossing over and going from diploid to haploid

going from diploid to haploid and having two rounds of cell division

independent assortment and crossing over

independent assortment and going from diploid to haploid

Correct. Although there are two rounds of cell division in meiosis and cells go from being diploid to haploid, neither of these two features automatically results in genetic differences among cells. Genetic diversity among meiotic products (gametes) is generated by both independent assortment of homologous chromosomes on the metaphase plate, and crossing over of non-sister chromatids.

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Incorrect. Although there are two rounds of cell division in meiosis and cells go from being diploid to haploid, neither of these two features automatically results in genetic differences among cells. Genetic diversity among meiotic products (gametes) is generated by both independent assortment of homologous chromosomes on the metaphase plate, and crossing over of non-sister chromatids.

Question

In the absence of crossing over, which formula best represents the number of possible different arrangements of chromosomes generated by independent assortment?

2ⁿ, where n represents the number of chromosomes per cell entering meiosis

2n, where n represents the number of chromosomes per cell entering meiosis

n², where n represents the number of homologous chromosome pairs per cell entering meiosis

2ⁿ, where n represents the number of homologous chromosome pairs per cell entering meiosis

2n, where n represents the number of homologous chromosome pairs per cell entering meiosis

Correct. If there are only two homologous chromosomes, it is obvious that only two arrangements are possible (either the maternally or paternally derived homolog will be on the right with equal probability). This eliminates “A” and “C” as possibilities, but all other choices still fit the observation. If there are two homologous chromosome pairs, there are four possible arrangements of chromosomes on the metaphase plate during meiosis one leaving “B,” “D,” and “E” as viable answers. However in the case of three homologous chromosome pairs, there are eight possible arrangements of chromosomes on the metaphase plate during meiosis I (see this for yourself in the animation). Only choice “D” fits this observation, and is, in fact, the correct formula.

You have one more chance to answer the question correctly. Try again.

Incorrect. If there are only two homologous chromosomes, it is obvious that only two arrangements are possible (either the maternally or paternally derived homolog will be on the right with equal probability). This eliminates “A” and “C” as possibilities, but all other choices still fit the observation. If there are two homologous chromosome pairs, there are four possible arrangements of chromosomes on the metaphase plate during meiosis one leaving “B,” “D,” and “E” as viable answers. However in the case of three homologous chromosome pairs, there are eight possible arrangements of chromosomes on the metaphase plate during meiosis I (see this for yourself in the animation). Only choice “D” fits this observation, and is, in fact, the correct formula.

Chapter 2.3. Animation Activity: Genetic Variation in Meiosis

Animation Assessment

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