A scientist doing research found that flower color and pollen shape were traits that were always passed together. That is, they did not fit Mendel's rule for independent assortment. Why might that be?
The genes responsible for flower color and pollen shape are 'linked' i.e. located very closely on same chromosome.
When genes are 'linked' crossing over can not take place freely between the genes . This leads to formation of gametes with more of parental combination of alleles, recombinants appear in less number.
Appearance of less than 50% recombinants in progeny will definitely disrupt predictions of independent assortment, i.e. normal dihybrid ratio.