You again want to map the positions of three genes (l, m, and n) in drosophila. each gene has one dominant allele and one recessive allele. you perform the three different two-fac- tor crosses (cross 1: lm and lm, cross 2: mn and mn, and cross 3: ln and ln). assume all crosses are between diploid flies homozy- gous for the alleles of these genes. you observe 5% recombinants in the first cross, 50% recombinants in the second cross, and 50% recombinants in the third cross. based on the data given, what can you determine for the gene order and distance between the genes?

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.