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Next Four Questions Table I shows the results of breeding experiments to examine the inheritance of flower color (purple versus white) and pod shape (inflated versus constricted). For the crosses recorded in Table 1, true-breeding parents were crossed to produce F, offspring, which were then testerossed to homozygous recessive individuals. Table I shows the results of computer-simulated crosses to model the inheritance of leaf shape (broad versus narrow) and flower color (purple versus white).
TABLE 1: RESULTS FROM CROSSES WITH PEA PLANTS
Parental Cross Phenotypes of F1 Offspring Phenotypes of Testcross Offspring (numbers of individuals)
Purple x White Purple Purple (461) White (468)
Inflated x Constricted Inflated Inflated (593) Constricted (588)
Purple, Inflated x White, Constricted Purple, Inflated Purple, Purple, White, White,
Inflated Constricted Inflated Constricted
(315) (312) (320) (317)
TABLE II: RESULTS OF COMPUTER-SIMULATED CROSSES
Parental Cross Phenotypes of F: Offspring Phenotypes of Testcross Offspring (numbers of individuals)
Broad x Narrow Broad Broad (4870) Narrow (4862)
Purple x White Purple Purple (4253) White (4259)
Broad, White x Narrow, Purple Broad, Purple Broad, Broad, Narrow, Narrow,
White Purple White Purple
(672) (75) (61) (664)
Based on the data in Table I, which of the following best explains why there are no individuals with constricted pods in the F1 generation?
(A)Inflated pod shape is dominant to constricted pod shape.
(B) The inflated-pod offspring in the Fi generation are homozygous.
(C) Constricted pod shape typically arises from a new mutation in the F generation.
(D) The constricted-pod offspring are carriers for the inflated pod shape allele
In Table I, the ratio of phenotypes in the offspring from the testcross with F1 plants that had purple flowers and inflated pods suggests that the genes for flower color and pod shape are located
(A) close together on the same autosome
(B) on the X chromosome
(C) on different chromosomes
(D) on a mitochondrial chromosomes
Which of the following provides the best justification for an assumption that might have been used in the computer simulation (Table II)?
(A) The broad allele is recessive to the narrow allele because broad leaves appear in every generation.
(B) The purple allele is dominant to the white allele because all the offspring from the cross of purple-flowered and white-flowered plants had purple flowers.
(C) The narrow allele is codominant with the purple allele because the purple-flower trait and the narrow-leaf trait segregate together.
(D) The white allele is dominant to both the broad and narrow alleles because plants with either type of leaf shape can have white flowers.