中国大学MOOC: 小鼠基因a和b相距40cM,AA BB和 aa bb 小鼠交配，F1代所产生配子(gametes)的基因型和比例为20% Ab and aB, 30% AB and ab。

Which of the following does not lead to the formation of aneuploid gametes? A: Failure of homologous pairs to separate at anaphase B: A mutatation in a single gene located on chromosome 2. C: A pair of sex chromosomes that does not separate during anaphase D: A set of sister chromotids that doest not separate during anaphase I

【多选题】A man has genotype A1A2 G1G2. (one each of the A1 and A2 alleles of gene A, one each of the G1 and G2 alleles of gene G ) The A and G loci are on difference chromosomes. What gametes will many meioses produce, in what proportions? A. 1/2  A1A2, 1/2  G1G2 B. 1/4  A1A1, 1/4 A1G1,  1/4 A2G1, 1/4 G1G2 C. 1/4 A1, 1/4 A2, 1/4 G1, 1/4 G2 D. 1/4 A1G1, 1/4 A1/G2, 1/4 A2G1, 1/4 A2G2 E. None of the above F. More information is needed