The principle of independent assortment is based on the fact that

Question

BlackTom AI · Accepted Answer

Question restatement: The principle of independent assortment is based on the fact that
- Option A: each set of sister chromatids is positioned independently at the metaphase plate of meiosis I.
- Option B: crossing over occurs within all pairs of homologous chromosomes.
- Option C: each homologous pair of chromosomes is positioned independently at the metaphase plate of meiosis I.
- Option D: each homologous pair of chromosomes is positioned independently at the metaphase plate of meiosis II.

Analysis of each option:
Option A: 'each set of sister chromatids is positioned independently at the metaphase plate of meiosis I.' This is incorrect because independent assortment concerns how paternal and maternal chromosomes (homologous pairs) align and separate, not the sister chromatids themselves. Sister chromatids are ultimately separated during anaphase II (and also during meiosis I for homologous chromosomes, but the concept of independent assortment refers to homologous chromosome orientation, not sister chromatid separation). The phrasing misattributes independence to sister chromatids and to meiosis I metaphase plate positioning.

Option B: 'crossing over occurs within all pairs of homologous chromosomes.' While crossing over does occur between nonsister chromatids of homologous chromosomes during prophase I, it is not the basis of the principle of independent assortment. Crossing over increases genetic recombination but independent assortment specifically refers to the random orientation of homologous chromosome pairs at metaphase I, not the occurrence of crossing over itself. Additionally, it is not accurate to claim it occurs within all pairs in every case.

Option C: 'each homologous pair of chromosomes is positioned independently at the metaphase plate of meiosis I.' This directly reflects the core idea of independent assortment: the orientation of one homologous pair is independent of the orientation of other pairs during metaphase I, leading to many possible combinations of maternal and paternal chromosomes in gametes. This aligns with Mendelian genetics and the mechanism by which genetic variation arises through independent alignment and separation.

Option D: 'each homologous pair of chromosomes is positioned independently at the metaphase plate of meiosis II.' This is inaccurate because independent assortment is classically described for metaphase I, where homologous pairs align and segregate. In meiosis II, the cells contain haploid sets, and there are no homologous chromosome pairs to orient independently in the same sense as metaphase I. Therefore, this statement misplaces the stage at which independent assortment operates.

In summary, option C correctly describes the foundational concept: the random, independent orientation of each homologous chromosome pair at metaphase I leads to independent assortment of alleles into gametes, whereas the other statements either misidentify the chromosomes involved (sister chromatids), attribute the concept to crossing over, or misstate the stage (meiosis II).

The principle of independent assortment is based on the fact that单项选择题

类似问题

Mendel’s law of independent assortment states that:

Mendel’s dihybrid crosses allowed him to postulate the law of independent assortment. Which statement best describes this law?

Genes segregate independently only if they

Question at position 2 Drosophila melanogaster has four pairs of chromosomes. Sperm from this species are formed by a meiotic process in which no crossing over occurs. How many genetically different kinds of sperm could be produced by a Drosophila melanogaster male?481664256

cl+gl+/clgl (F1 hybrids) x clgl/clgl (tester plants) If the chlorina and glabrous loci are assorting independently, then the cross above would be expected to produce F2 offspring with what phenotypic ratio?

Assume that genes A and B are not linked. If the probability of allele A in a gamete is 1/2 and the probability of allele B in a gamete is 1/2, then the probability that both A and B are in the same gamete is

Assume that genes A and B are not linked. If the probability of allele A in a gamete is 1/2 and the probability of allele B in a gamete is 1/2, then the probability that both A and B are in the same gamete is

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单