Answer these questions on TopHat, do not submit a written sheet. Note: there may

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Answer these questions on TopHat, do not submit a written sheet. Note: there may be more than one correct answer for some questions. You must choose all those that apply. (1) The flowers of daffodils can have many different colors. In separate breeding experiments, single daffodils with different flower colors (the parental phenotypes) were crossed and for four of these experiments some or all of the progeny had flowers with a different color (i.e. a new phenotype), as follows Progeny () All the progeny had the new phenotype (ii) 1/2 of the progeny had the new phenotype; 3/8 had one parental color and 1/8 had the other parental color. (iii) 1 /4 of the progeny had the new parental color; 3/4 had one parental color (the other parental color did not show up in the progeny) (iv) 1/4 of the progeny had the new parental color; 1/2 had one parental color, and 1/4 had the other parental color. In regard to the number of genes controlling flower color, alleles and the relationship between these alleles, what are the possible explanations for (i) - (iv) to account for the observations Possibilities A One gene; two alleles one completely dominant over the other, one parent is heterozygous B One gene; incomplete dominance; parents are homozygous for different alleles C One gene; multiple alleles one completely dominant over the other; parents are heterozygous for different alleles D Two genes, two alleles each; complete dominance for one allele for each gene; parents are homozygous for different alleles E Two genes; two alleles each; complete dominance for one allele for each gene; one gene is recessively epistatic to the other, one parent is a double heterozygote the other heterozygous for one gene and homozygous for the other. More than one possibility may explain the progeny phenotype(s), you must select all to get the points (1 point each 4 points total) (2) Siberian rats can have short or long hair, black, grey or white hair, and can have straight or curly tails Each trait is controlled by a single gene. The allele for long hair is completely dominant over that for short; the allele for black hair is incompletely dominant over that for white and the allele for straight tails is completely dominant over that for curly. Pure breeding long-haired, white, straight-tailed rats were crossed to pure- breeding short-haired, black, curly-tailed rats and the F1 progeny were crossed to themselves. What is the fraction of the F2 progeny that will be short-haired, grey and curly-tailed? (4 points) A 1/2 132 1/16 D 3/32

Explanation / Answer

Question 1-

Two options C and E are having possible explanations because in the first case when all progenies have different phenotypes, it suggests that parents are heterozygous and one allele has complete dominant because it must express one main parent phenotype. One allele must have recessive epitasis to express a new phenotype. Therefore, the option E is also correct.

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