Post-Lab Questions
Part 2: Monohybrid Cross
1. How much genotypic variation do you find in the randomly picked parents of your crosses?
2. How much in the offspring?
3. Pool all of the offspring from your five replicates. How much phenotypic variation do you find?
4. Is the ratio of observed phenotypes the same as the ratio of predicted phenotypes? Why or why not?
5. What is the difference between genes and alleles?
Gene is what determines a particular trait where as allele can occur in a fixed spot of the chromosome.
6. How might protein synthesis execute differently if a mutation occurs?
The mutant protein will then form.
7. Organisms heterozygous for a recessive trait are often called carriers of that trait. What does that mean?
It means that they carry the gene for a certain trait but they don’t express the trait because they only have one gene for it and not two.
8. In peas, green pods (G) are dominant over yellow pods. If a homozygous dominant plant is crossed with a homozygous recessive plant, what will be the phenotype of the F1 generation? If two plants from the F1 generation are crossed, what will the phenotype of their offspring be?
Three green plants and one yellow Part 3: Dihybrid Cross
1. How similar are the observed phenotypes in each replicate?
2. How similar are they if you pool your data from each of the five replicates?
3. Is it closer or further from your prediction?
closer
4. Did the results from the monohybrid or dihybrid cross most closely match your predicted ratio of phenotypes?
5. Based on these results; what would you expect if you were looking at a cross of 5, 10, 20 independently sorted genes?
6. Why is it so expensive to produce a hybrid plant seed?
Due to the amount of research it takes to develop and other efforts that go into the final production.
7. In certain bacteria, an oval shape (O) is dominant over round (o) and thick cell walls (T) are dominant over thin (t). Show a cross between a heterozygous oval, thick cell walled bacteria with a round, thin cell walled bacteria. What are the phenotype of the F1 and F2 offspring?
The resulting will be more recessive and less dominant characters as, Oval- Thick walled is a Carrier
and others display Recessive Traits
