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Using the forked-line, or branch diagram, method, determine the genotypic and
HINT: This problem asks you to use the forked-line method to determine the outcome of a number of trihybrid crosses. The key to its solution is to realize that in using the forked-line method, you must consider each gene pair separately. For example, in this problem, first predict the outcome of each cross for the A/a genes, then for the B/b genes, and finally, for the C/c genes. Then you are prepared to pursue the outcome of each cross using the forked-line method.
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- In onion, male sterility is produced when the nuclear genotype is aa and the mitochondrial gene S (sterile) are present. Any other combination of nuclear genotype and mitochondrial gene (including gene F for fertile) will result in a male fertile plant. Give the genotypic ratio and the phenotypic ratio or the percentage of male sterile and male fertile offspring that will be produced in the following crosses. 1. Aa + S male x aa + F female 2. Reciprocal cross of number 1. (Note that when we do reciprocal cross, we interchange/swap the genotypes of the parents (if there is a nuclear gene involved, you interchange the nuclear genotype as well). 3. Aa + S female x Aa + F male 4. Reciprocal cross of number 3.arrow_forward):):));;$;$:&:&:arrow_forwardHow many different kinds of F1 gametes, F2 genotypes, and F2 phenotypes would be expected from the following crosses: (a) AA x aa; (b) AA BB x aa bb; (c) AA BB CC x aa bb cc? (d) What general formulas are suggested by these answers?arrow_forward
- Consider the cross AaBbCC x AABbCc a) How many different gamete genotypes can each organism make? b) Predict the phenotypic ratios of the offspring using either a punnet square or forked line method.arrow_forwardIn snapdragons, red flower color (R) is incompletely dominant over white flower color (r). The hybrids or heterozygous plants (Rr) are pink in color. a) Show the genotype for a white flower and for a red flower. b) If a red-flowered plant is crossed with a white-flowered plant, what are the genotypes and phenotypes of the F1 generation plants? c) What genotypes and phenotypes will be produced in the F2 generation? d) How did the genotypic and phenotypic ratio compare to each other in this incomplete dominance cross? e) What would the phenotypic ratio have been if this had been complete dominance? f) What kind of offspring can be produced if a red-flowered plant is crossed with a pink-flowered plant? g) What kind of offspring is/are produced if a pink-flowered plant is crossed with a white-flowered plant?arrow_forwardThe allele G for yellow stigma is completely dominant to green (g). Supposing two strains of autotetraploid plants are available and their genotypes are as follows: GGgg – in this plant the gene is close to the centromere Gggg – in this plant the gene is far from the centromere If these two plants are crossed: a) provide the gametes that can be obtained from the two plants; b) provide the genotypic and phenotypic ratios of the offspring.arrow_forward
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