Question

a scientist is studying the inheritance of two characteristics in plants: red flowers (rr and rr), which are dominant to yellow flowers (rr), and green leaves (gg and gg), which are dominant to yellow leaves (gg). she crosses a double heterozygous (rrgg) with a double recessive (rrgg), and expect to see a 1 : 1 : 1 : 1 ratio in the offspring. instead, she sees these results: | genotype | rrgg | rrgg | rrgg | rrgg | | --- | --- | --- | --- | --- | | predicted outcome | 500 | 500 | 500 | 500 | | actual outcome | 900 | 900 | 100 | 100 |

Explanation:

The cross is a test cross (double heterozygous × double recessive). A 1:1:1:1 ratio is expected if genes assort independently. The actual results show more parental genotypes (RrGg, rrgg) and fewer recombinant genotypes (Rrgg, rrGg), indicating the genes are linked on the same chromosome, so they do not assort independently.

Answer:

The genes for flower color and leaf color are linked (located on the same chromosome), leading to non-independent assortment.