IMG_0002 - Midterm Exam BioSci 110 Spring 09 RUBRIC 6—8...

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Unformatted text preview: Midterm Exam, BioSci 110, Spring 09 RUBRIC 6—8. Wing shape is a trait NOT related to DDT resistance. The gene for wing shape is found on a separate somatic chromosome. Bent wings (B) are dominant; straight wings (b) are recessive, Recall, resistance to DDT is recessive (r); non-resistance (R) is dominant. 6, [2 pts] What is the genotype for a mosquito that has straight wings and carries the resistance allele? Genotype: bbRr (1pt: bb;1pt: Rr) 7. [14 pts] Draw the chromosomes for this mosquito (straight wings and carries the resistance allele), at each of the phases of MEIOSlS described below. Label all alleles (B, b, R, r), sister chromatids, and homologous chromosomes. Circle the chromosomes to indicate how many CELLS there are at each stage. b. [2 pts] Metaphase of meiosis 1 (when the homologous pairs line up). a. [4 pts] G2 phase (after DNA replication). - 4 chromosomes . correct genotype is represented chromosomes are in the replicated state: - sisters are identical 0 centromeres link sisters o chromosomes are in the replicated state and lined up in pairs at the equatorial plane . homologous chromosomes are opposite one another at the equatorial plane c. [4 pts] Metaphase of meiosis 2 (before the sister chrom atids separate). cl. [4 pts] Products of meiosis (the gametes). o 4 cells . each cell contains 2 chromosomes 0 I 2 cells - each cell has 1 member from the homologous pair (ploidy is reduced) 0 chromosomes are in the replicated state aligned by centromeres at the equatorial plane chromosomes are unreplicatecl gametes are haploid — 1 member from each homologous pair, following from division of each M2 cell 8. [11 pts] Predict the outcome of a cross between the following mosquitoes: Parent 1: straight wings, carrier of resistance allele (this is the mosquito from Q6 and 7, above) Parent 2: heterozygous for wing shape, resistant to DDT. a. [2 pts] Genotype of Parent 2; Bbrr llptl Bb; llp] N b. [2 pts] Predict the genotypes of gametes formed by Parent 1: bR and br c. [2 pts] Predict the genotypes of gametes formed by Parent 2: Br and br ...
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