Question

Assume that an organism exists in which crossing over does not occur, but that all other processes associated with meiosis occur normally. Consider how the absence of crossing over would affect the outcome of a single meiotic event. Which of the following statements would be true if crossing over did not occur?

Answer 1

Answer:

The options are missing, they are:

a.The daughter cells of meiosis I would be diploid, but the daughter cells of meiosis II would be haploid.

b.The two sister chromatids of each replicated chromosome would no longer be identical.

c.The four daughter cells produced in meiosis II would all be different.

d.The two daughter cells produced in meiosis I would be identical.

e.There would be less genetic variation among gametes.

f.Independent assortment of chromosomes would not occur.

The correct answer is E, there would be less genetic variation among gametes.

Explanation:

Crossing-over or also called recombination is a phenomenon peculiar to meiosis alone. Meiosis is that kind of division that is employed by sexual-reproducing organisms to produce gamete/sex cells. Crossing-over is a process that may or may not occur, if it does, it occurs in prophase of meiosis I, and it involves exchanging equal chromosomal segments between two non-sister chromatids or homologous chromosomes. Crossing-over is the means by which sexually reproducing organisms use to bring about genetic variation among their species.

It is worthy to note that the non-occurrence of crossing-over does not affect the number of chromosomes as a normal meiotic division will always yield haploid gametes right from meiosis I.

Since crossing-over did not occur, the homologous chromosomes (similar but non-identical chromosomes) will separate into each cell during meiosis I, meaning that each cell will have chromosomes that are either maternal or paternal. This will reduce the chance of genetic variation occuring among species.