You identify a rare purple plumed parrot. when you cross the parrot to a true breeding white parrot, you get ½ white and ½ purple parrots. when you cross two purple parrots you get 1/3 white parrots and 2/3 purple parrots. which of the following best explains this result? a. the purple allele is lethal in the homozygous state. b. white is dominant to purple. c. the white allele is lethal in the homozygous state. d. the purple allele is lethal in the heterozygous state.

a. The purple allele is lethal in the homozygous state

Explanation:

You cross a purple parrot with a true breeding (homozygous) white parrot and you get 1/2 purple parrots and 1/2 white parrots. This result can only happen if the purple parrot is heterozygous and the white parrot is homozygous recessive (if any of the parents had been homozygous dominant, 100% of the offspring would have had the dominant phenotype).

Then: Pp (purple) X pp (white) ---> 1/2 Pp, 1/2 pp

When you cross two purple parrots you get 1/3 white parrots and 2/3 purple parrots. The 2:1 phenotypic ratio is typical of a lethal allele in the homozygous state.

In a cross of two purple parrots: Pp

X Pp, one would expect the genotypic ratios 1 PP : 2 Pp : 1pp and the phenotypic ratios 3 Purple : 1 white.

But the PP genotype is lethal, so those individuals die and the only purple parrots we see are the heterozygous ones.

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measuring physical properties lab reportinstructions: in the physical properties lab, you will test the physical properties of different building materials in order to pick the appropriate materials for a new home in tiny world. record your observations and test measurements in the lab report below. youwill submit your completed report.name and title: lyric lawton, mr.herbert, 10/13/17, physical properties lab. objective(s): i need to parvus build his house out of the right material, so he will stay cool in the mountains.hypothesis: if we use wood to build the roof of the house, then the temperature inside the house will remain cooler.if we use clay brick to build the walls and floors of the house, then the temperature inside the house will remain cooler.if we use aluminium to bring electricity into the home, then it will allow electricity to flow into the home at a faster rate.if we use iron to construct the latches on the windows and doors, then the magnetism will keep the latches secure.