Use the following information to answer the 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 performed a testcross with an organism that had been found to be heterozygous for the three recessive traits, and she was able to identify progeny of the following phenotypic distribution (+ = wild type):

The greatest distance among the three genes is between a and c. What does this mean?
A) Gene c is between a and b.
B) Genes are in the order: a-b-c.
C) Gene a is not recombining with c.
D) Gene a is between b and c.

Question

Use the following information to answer the 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 performed a testcross with an organism that had been found to be heterozygous for the three recessive traits, and she was able to identify progeny of the following phenotypic distribution (+ = wild type):

The greatest distance among the three genes is between a and c. What does this mean?
A) Gene c is between a and b. 
B) Genes are in the order: a-b-c. 
C) Gene a is not recombining with c. 
D) Gene a is between b and c.

Quizplus · Accepted Answer

The greatest distance among the three genes means that they are farthest apart from each other on the chromosome. As gene a and gene c are the farthest apart, the order would be a-b-c. Therefore, option B is correct.

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