Q84 - Mapping Linked Genes from a Four-Gene Testcross
An organism has four genes, A, B, C and D with two alleles each. An individual heterozygous for these genes was bred with one that is homozygous recessive. The cross produced 3288 offspring with phenotypes shown in the table below:
| Phenotype | Number of individuals |
|---|---|
| A B C D | 675 |
| A B C d | 83 |
| A B c D | 1 |
| A B c d | 74 |
| A b C D | 73 |
| A b C d | 1 |
| A b c D | 84 |
| A b c d | 670 |
| a B C D | 655 |
| a B C d | 86 |
| a B c D | 1 |
| a B c d | 73 |
| a b C D | 71 |
| a b C d | 1 |
| a b c D | 87 |
| a b c d | 653 |
Indicate in the answer sheet if each of the following statements is true or false.
Using the information and data, determine which of the statements are true or which are false.
A. The four loci are genetically linked.
B. The distance between gene B and gene D is 9 cM.
C. The distance between gene D and gene C is 10.5 cM.
D. Interference happened with a value less than 0.25. Interference = 1-(observed frequency of double crossover/expected frequency of double crossover).
Question reproduced from IBO 2016, Theoretical Paper B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)