Question

6-Mary is .Aa, and allele "a. is her paternal copy. Mary's half-sister (different fathers) is aa". what proportion of the sperm cells of Mary's brother (with the same parents as Mary) will have 'allele#7 A- All of them B- All of the X bearing sperm C-50% ofthe X bearing sperm, none ofthe Y bearing sperm D- None of them ⓟcan't tell. It depends on the genotype of Mary's brother coples present in the first polar body). The gamete (the egg cell) she produced this month should have contained: 7- Ruth's genotype is MmiSs. The first polar body she produced this month carried mmss (all the gene A- M andS B- S and s C- M to S in a ratio of 3:1 D- M and s E- m and s F. A or D G-A or E 8- Genes B and D are located on the same chromosome. Mark is -BbDd" and the sperm that made him was Bd. A crossing over occurs at lecus B of one of his primary spermatocytes (this means a crossing over occurs between two non-sister chromatids so that the B and b alleles of this chromosome are exchanged). fow many copies of allele B would be present in each of the resulting secondary spermatocyte in prophase 11? One B- Two C-Four D- both A and B are possible 9- In the question above, how many types of sperm with regard to the alleles of genes B and D will be produced from that primary spermatocyte? A- One B- Two C- Four D- Can't tell. Could be two or four types 10- Sue is AaBbee for three types of genes located on three different chromosomes. What proportion of Sue's egg cells would carry Abe throughout her life? Hint: Every gamete carries only one copy of each and every gene. A- Zero 12.5% 25% D-50% E-33% F-75% G- All

Answer 1

6) The genotype of Mary is Aa. The genotype of her half sister is aa. Therefore, Mary's mother is heterozygous with the genotype Aa. Her father has a allele and his genotype is a_. Therefore, the genotype of Mary's brother is either a_ or A_. Hence Mary's brother will produce sperms in which there is 50 % Probability of having a allele in X chromosome (option c).