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Genes A, B, C, and D are located on the same chromosome. The recombination frequencies (RF) are as follows:What is the most likely order of the genes on the chromosome?Relationship. RFA-B. 8%A-C. 23%A-D. 19%B-C. 10% C-D. 52%

Correct answer: B. CBAD

  • A. BCAD
  • B. CBAD
  • C. ACBD
  • D. ABCD

Explanation

The correct order of genes on the chromosome is CBAD. This order is determined by analyzing the recombination frequencies: a larger RF indicates a greater distance between genes. Here, C and D have the largest RF (52%), suggesting they are the farthest apart. Therefore, they should be positioned at opposite ends of the chromosome. A and B, with smaller RFs (8% and 10%), must be placed in between C and D, reflecting their closer linkage. The other options fail to accurately represent these distances, leading to incorrect arrangements.

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Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.

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