Concept explainers
Red eyes is the wild-type
Cross 1: Males with vermilion
354 offspring, all with red eyes
Cross 2: Males with
212 male offspring with vermilion eyes
221 female offspring with red eyes
Explain the pattern of inheritance based on these results. What additional crosses might you make to confirm your hypothesis?
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Genetics: Analysis and Principles
- Figure 8.10 In pea plants, purple flowers (P) are dominant to white (p), and yellow peas (Y) are dominant to green (y). What are the possible genotypes and phenotypes for a cross between PpYY and ppYy pea plants? How many squares would you need to complete a Punnett square analysis of this cross?arrow_forwardThe following pedigree shows the pattern of inheritance of red-green color blindness in a family. Females are shown as circles and males as squares; the squares or circles of individuals affected by the trait are filled in black. What is the chance that a son of the third-generation female indicated by the arrow will be color blind if the father is not color blind? If he is color blind?arrow_forwardYou are doing a cross with Drosophila using the following two traits. Curly wings is dominant over straight wings, and round eyes is dominant over elliptical eyes. You cross a female fly that is known to be heterozygous for both genes with a male that is heterozygous for the wing gene but has elliptical eyes. This cross produces 74 flies with curly wings and round eyes, 61 with curly wings and elliptical eyes, 24 with straight wings and round eyes, and 21 with straight wing and elliptical eyes. Calculate the expected phenotype ratios for this cross, then use the chi-square test to see if the observed data are consistent with the expected numbers.arrow_forward
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- In corn, two independent, recessive nuclear genes, japonica (j) and iojap (ij), produce variegation (green and white striped leaves). Matings between individuals heterozygous for japonica always produce 3 green:1 striped individuals regardless of how the cross is performed. You have a variegated plant that could be either jj or ijij . What cross can you make to determine the genotype of this plant, and what results do you expect in the F1 generation in each case?arrow_forwardAnother cross in Drosophila involved the recessive, X-linked genes yellow (y), white (w), and cut (ct). A yellow-bodied, white-eyed female with normal wings was crossed to a male whose eyes and body were normal but whose wings were cut. The F1 females were wild type for all three traits, while the F1 males expressed the yellow-body and white-eye traits. The cross was carried to an F2 progeny, and only male offspring were tallied. On the basis of the data shown here, a genetic map was constructed. Phenotype Male Offspring y + ct 9 + w + 6 y w ct 90 + + + 95 + + ct 424 y w + 376 y + + 0 + w ct 0 (a) Diagram the genotypes of the F1 parents. (b) Construct a map, assuming that white is at locus 1.5 on the X chromosome. (c) Were any double-crossover offspring expected? (d) Could the F2 female offspring be used to construct the map? Why or why not?arrow_forwardIn Drosophila, singed bristles (sn) and cut wings (ct) are both caused by recessive, X-linked alleles. The wild type alleles (sn+ and ct+) are responsible for straight bristles and intact wings, respectively. A female homozygous for sn and ct+ is crossed to a sn+ct male. The F1 flies are interbred. The F2 males are distributed as follows: genotype number sn ct 15 sn ct+ 34 sn+ ct 33 sn+ct+ 18 What is the map distance between sn and ct?arrow_forward
- In a unique species of plants, flowers may be yellow, blue, red, or mauve. All colors may be true breeding. If plants with blue flowers are crossed to red-flowered plants, all F1 plants have yellow flowers. When these produced an F2 generation, the following ratio was observed: 9/16 yellow: 3/16 blue: 3/16 red: 1/16 mauve In still another cross using true-breeding parents, yellow-flowered plants are crossed with mauve-flowered plants. Again, all F1 plants had yellow flowers and the F2 showed a 9:3:3:1 ratio, as just shown. (a) Describe the inheritance of flower color by defining gene symbols and designating which genotypes give rise to each of the four phenotypes. (b) Determine the F1 and F2 results of a cross between truebreeding red and true-breeding mauve-flowered plants.arrow_forwardIn roses, purple flower color is determined by the dominant P allele, while pp homozygotes are white. The presence of long stems is determined by the dominant S allele, while ss homozygotes have short stems. Both mutations are completely penetrant. A test cross was performed between a rose plant of unknown genotype with a white flowered, short stemmed rose plant (pp ss) and the following 200 progeny plants were obtained: 84 white flowers, long stems 16 purple flowers, long stems 82 purple flowers, short stems 18 white flowers, short stems Select the statements below that are TRUE. Select 2 correct answer(s) The P and S genes independently assort during meiosis. The map distance between P and S is 17 CM. The genotype of the progeny plants with purple flowers and short stems is PP ss. The map distance between P and S is 83 CM. The homologs in the plant with unknown genotype are p S and Ps. The homologs in the plant with unknown genotype are PS and p s.arrow_forwardA parental cross between homozygous wild-type red eyed females (X+ X+) were crossed with white eyed males (XwY). The F1 generation consisted of phenotypic X+Xw females and X+Y males. The F2 generation was produced by crossing the F1 generation and consisted of a ratio of 2 red eyed females (X+ X+ and X+ Xw) : 1 red eyed male (X+Y) : 1 white eyed male (XwY). Attached is a picture of a chi square analysis based on the results from the F2 generation. Please discus what conclusions can be made based on the data/findings. What inheritance pattern is this?arrow_forward
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