Post-Section Problems A Answer Key.docx

Post-Section Problems A Answer Key.docx - Post-Section...

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Post-Section Assignment A Post-Section Assignment A (Released on Wed Oct 11 7pm, due Wednesday Oct 18 11:59 pm). All answers must be typed, except where noted. Answers must be within the boxes and lines provided, font size must be 11 or greater. Points were deducted for answers that exceeded the space provided. The 2017 Nobel prize in Medicine recognized the field of circadian biology—that plants and animals have daily cycles. This phenomenon was described in the 1700’s already in plants! This may not be surprising because, as photosynthetic organisms, plants are very tied into day/night cycles. They can actually “tell time” by integrating circadian rhythms with day length and use this information to tell when to flower and reproduce. Among European peas like the ones Mendel studied, field trials have identified variants that flower at different times of the season, even when all planted on the same day. You find 4 phenotypic classes (shown in table below) : those that flower in May, in June, in July and in August. Part 1 You would like to determine the genetic basis of flowering time in these European peas, so you perform the following genetic crosses and examine the flowering timing of the first 100 offspring plants produced. See table below. Then answer questions a-f that follow. Important Note: In each of these crosses, you are using a different set of parent A and parent Bs, so don’t assume that all parents with a particular phenotype will have the same genotype. Cross # Parent A x Parent B Progeny Ratios Earliest flowering May (Takes 1 month to flower) Early intermedia te flowering June (Takes 2 months to flower) Late Intermedia te flowering July (Takes 3 months to flower) Latest flowering August (Takes 4 months to flower) 1 May x June 50 50 0 0 2 June x Aug 0 50 0 50 3 July x July 33 0 67 0 4 Aug x Aug 0 33 0 67 5 June x July 50 0 0 50 6 May x May 75 25 0 0 7 * hard! May x July 50 0 25 25 1 1
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Post-Section Assignment A 2 2
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Post-Section Assignment A To help you answer, as you work through the crosses, fill in the following information requested in a-d . In part e , describe your complete model in the box provided. a) How many genes appear to be involved? Give a different letter designation for each gene. Call the first flowering gene F1, the second flowering gene F2, etc. and list them below. b) List all alleles of each flowering time gene and specify the phenotype associated with each allele using the following convention: For each flowering time gene, designate the allele by using the phenotype of the allele as superscript. For example, F1 May is the May allele of the F1 gene and results in earliest flowering. *TA note: I took off points throughout for misusing words such as gene and allele. c) Using the allele symbols you have defined above, determine dominance, co- dominance, and incomplete dominance relationships between different alleles at each locus. In each case, indicate one key cross that supports each relationship.
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