Let’s say you are studying stem length in tulips. This trait determined by a number of polygenes. If there are nine phenotypic categories, how many genes are involved in tulip stem length?

You are working with a hypothetical fly and have found color and wing mutants. Preliminary work indicates that the mutant traits are recessive and the associated genes are not sex-linked, but beyond that, you have no information. You first look at 2 genes, each with 2 alleles. "B" or “b" for body color and "W" or "w" for wing surface. The red-body phenotype is dominant to the yellow-body phenotype and smooth wings are dominant to crinkled wings.

A farmer who wants to enter the milk industry has purchased a modest venture of 12 heterozygous cows in the herd, all with two dominant cis-linked genes:production of a high volume of milk (+) and a high fertility (+). Recessive alleles (a) and (b), respectively, are present. On chromosome 3, the two genes are 25 cM apart. Bulls owned by two of the farmer's close neighbors are heterozygous for these characteristics as well. The second neighbor's bull has one dominant and one recessive allele from each characteristic on each homolog, but the first neighbor's bull shares the same alleles linked to his cows. 1. What parental genotypes should be crossed if the farmer wants to produce the most calves with high milk output and high fertility? 2. What are the F1 phenotypic frequencies of the cross between the farmer's bull and that of his first neighbor?

By conducting testcrosses, researchers have found that the sweetpea has seven linkage groups. How many chromosomes would youexpect to find in leaf cells of the plants?

Hybridization of a homozygous dominant and homozygous recessive plant was conducted. What is the probability that the F2 progeny will have the both pink flowers and fruits?

Imagine you are given two tall plants, but you do not know their genotype (see Figure 16-12). There are three possibilities—they might both be TT or both Tt or one TT and the other Tt. Imagine you cross the two plants, wait for them to produce seeds, and then plant the seeds. If all resulting plants are tall, can you then determine what the genotypes of the two parents are? If approximately half the resulting plants are tall and about half are short, can you then figure out the genotypes of the parents?

Hybridization of a homozygous dominant and homozygous recessive plant was conducted. What is the probability that the F2 progeny will have the phenotype green big leaves, with pink flowers having both small and big petals?

A farmer is interested in a novel colour pattern in beans. This trait is controlled by a single autosomal gene (Gene G) with two alleles. The G-allele results in a striped bean, while the recessive g-allele causes a brown bean. The farmer has a plant that has striped beans. Can you suggest how the farmer can determine the genotype (GG or Gg) of his bean plant in a single cross? Describe this cross and provide details on how you would interpret the results

If an allotetraploid species is made up of two ancestral genomes, A and B, with each of them having a basic chromosome number of seven.  The resistance to the pathogen attacking the foliage of plants is controlled by a dominant allele located at the F locus.  The recessive alleles F^a and F^b show sensitivity to the pathogen.  Plants with at least on F^A allele are resistant to the pathotype 1 and 2 (regardless of the genotype in B genome), and plants with at least one F^B allele are resistant to pathotypes 1 and 3 (regardless of genotype in A genome).  What proprtion of the self-progeny of F^AF^a F^BF^b plant will be resistant to pathotype 1, 2 and 3?

Mendel obtained his initial pea plant varieties from local breeders who were developing new varieties that might be useful or interesting. To generate these new varieties, breeders formed hybrids between existing varieties of different phenotypic characteristics by cross pollination, using techniques they doubtless taught to Mendel.  After producing a hybrid, they allowed several generations of self-pollination, as happens naturally if the flowers are not disturbed. a. What if a breeder were working with 7 different, independently segregating genes, as Mendel did? How many generations would it take him to have pure-breeding varieties, starting from an F1 hybrid that is heterozygous for all 7 genes?    i. What is the probability that an individual in the F2 generation would be pure-breeding (i.e. is homozygous at all 7 loci)? [Hint: this is an “and” calculation since it must be homozygous at each of the 7 loci.    ii. What is the probability that an individual in the F3 generation would…