Science Homework Help

Pure-breeding ancient varieties of chickpeas can be black, brown, green or red in color. A new cream colored chickpea was isolated and shown to be pure-breeding. To determine the genetic basis of color inheritance in chickpea many crosses were made between the various varieties. The results are shown in the table below.

Cross	F1 phenotype	F2 offspring ratio	Cross	F1 phenotype	F2 offspring ratio
black x brown	all black	¾ black ¼ brown	brown x red	all red	¾ red ¼ brown
black x green	all black	¾ black ¼ green	brown x cream	all tan	¼ brown ½ tan ¼ cream
black x red	all black	¾ red ¼ black	green x red	all green	¾ green ¼ red
black x cream	all black	¾ black ¼ cream	green x cream	all green	¾ green ¼ cream
brown x green	all green	¾ brown ¼ green	red x cream	all red	¾ red ¼ cream

A. Analysis of the F₂ offspring indicates that a single gene locus determines skin color in chickpea. Explain why?

B. From the choices below, determine which mode of inheritance controls chickpea skin color in the ancient varieties?

Complete Dominance
Incomplete Dominance Series
Codominance
Dominance Series
Lethal Genes
Recessive Epistasis
Dominant Epistasis

C. List the dominance relationship between the alleles of the ancient varieties of chickpea (black, brown, green, and red)

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D. What mode of inheritance controls the new cream chickpea skin color?

E. Give the genotypes of the following chickpeas (use B and b as your allele symbols):

Brown Tan Cream