A plantlike organism on the planet Pandora can have three recessive genetic traits: bluish leaves,due to an allele (a)of gene A;a feathered stem,due to an allele (b)of gene B;and hollow roots,due to an allele (c)of gene C.The three genes are linked and recombine.
A geneticist did a testcross with an organism that had been found to be heterozygous for the three recessive traits and was able to identify progeny of the phenotypic distribution (+ = wild type)shown in the figure below.
Which of the following are the phenotypes of the parents in this cross?
A)2 and 5
B)1 and 6
C)4 and 8
D)3 and 7
E)1 and 2

Question

A plantlike organism on the planet Pandora can have three recessive genetic traits: bluish leaves,due to an allele (a)of gene A;a feathered stem,due to an allele (b)of gene B;and hollow roots,due to an allele (c)of gene C.The three genes are linked and recombine.
A geneticist did a testcross with an organism that had been found to be heterozygous for the three recessive traits and was able to identify progeny of the phenotypic distribution (+ = wild type)shown in the figure below. 
Which of the following are the phenotypes of the parents in this cross?
A)2 and 5 
B)1 and 6 
C)4 and 8 
D)3 and 7 
E)1 and 2

Quizplus · Accepted Answer

Only the parents with the genotype aabbcc can produce offspring of the given phenotypic distribution. From the progeny, we know that two of them must have the genotype aabbCC (phenotype 1), two must have AABBcc (phenotype 2), one must have AAbbCc (phenotype 3), one must have aaBbCC (phenotype 4), two must have aaBBcc (phenotype 5), and two must have AAbbCC (phenotype 6). The only way to get these offspring is if the parent with the AAbbCc genotype (phenotype 3) also has heterozygous alleles for genes A and C (AaBbCc), and the parent with the aaBBCC genotype (phenotype 4) also has heterozygous alleles for genes B and C (AabbCc). Therefore, the only choice that satisfies this requirement is C, with parents 4 and 8 having the genotypes aaBBCC and AaBbCc, respectively.

A Plantlike Organism on the Planet Pandora Can Have Three