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1 | | Because of the way that Creighton and McClintock set up their crosses, there is some ambiguity with regard to phenotype and recombination. For example, colored/starchy kernels could occur in the presence or absence of crossing over. How could the crosses be modified to prevent such ambiguity? |
| | A) | Change parent A so that both dominant alleles are on the knobbed/ translocation chromosome. |
| | B) | Change parent A so that both dominant alleles are on the normal chromosome. |
| | C) | Change parent B so that it is homozygous for both recessive alleles (ccwxwx). |
| | D) | Change parent B so that it is heterozygous for both genes (CcWxwx). |
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2 | | Compared with traits that affect plant morphology, such as tall versus dwarf, why are kernel phenotypes a technically easier option? |
| | A) | You don't have to wait for the seed to germinate and the plant to grow. |
| | B) | There are many kernels on one cob. |
| | C) | Each kernel is relatively small, yet it represents one offspring. |
| | D) | All of the above |
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3 | | If the cross was changed so that parent A had both dominant traits on the knobbed/ translocated chromosome, and both recessive traits on the normal chromosome, and parent B was kept the same as the original experiment, which phenotypes would have to be due to crossing over? |
| | A) | Colored, waxy |
| | B) | Colored, waxy and colorless, waxy |
| | C) | Colorless, waxy |
| | D) | Colorless, waxy and colored, starchy |
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4 | | If the cross was changed so that parent B was homozygous recessive for both genes (ccwxwx) and parent A was kept the same as the original experiment, which phenotypes would have to be due to crossing over? |
| | A) | Colored, waxy |
| | B) | Colored, waxy and colorless, waxy |
| | C) | Colorless, waxy |
| | D) | Colorless, waxy and colored, starchy |
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5 | | In the cross described in Experiment 5A, on rare occasions it is possible to observe a kernel that is colorless/waxy yet does not contain a knobless/translocation chromosome. If we assume that new mutations do not occur in either gene, how could this occur? |
| | A) | A double crossover, one between both genes and one between the wx gene and the translocation |
| | B) | A double crossover, both of which occurred between the two genes |
| | C) | A double crossover, one between both genes and one between the C gene and the knob |
| | D) | A or C |
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