Question

Genetics:

1) Gametogenesis in Neuropsora is different from gametogenesis in humans and fruit flies in that it includes:

a) Only Meiosis II (i.e., Meiosis I does not occur)

b) Mitosis

c) Unordered gametes

d) Only Meiosis I (i.e., Meiosis II does not occur)

2) Assume that a true-breeding female with the dominant phenotype is crossed to a true-breeding male with the recessive phenotype (Generation 0). Female offspring are then backcrossed to males with the recessive phenotype (Generation 1). This process is then repeated, with each new generation created by crossing the female offspring from the previous backcross generation to males with the recessive phenotype. If this trait is controlled by a maternal effect gene, in which backcross generation will some of the females used for the backcross have the recessive phenotype?

a) 4

b) None. The recessive phenotype will never reappear with this crossing scheme.

c) 1

d) 3

e) 2

3) Consider the following parental cross, involving genes A and B that are located 10 cM apart on the same chromosome:

AB/AB x ab/ab

If the F1 individuals are backcrossed to the ab/ab parent, what percentage of the offspring are expected to have the genotype ab/ab?

Express your answer as an integer between 0 and 100.

4) Consider a dihybrid cross in which one allele at each of the two genes contributes a value of 2 to a trait whereas the other allele contributes 0.

What proportion of offspring are expected to have a phenotype of 4?

Enter your answer as a decimal with two places (e.g., 0.10 or 0.01).

Answer 1

1. Gametogenesis in Neuropsora is different from gametogenesis in humans and fruit flies in that it includes: b) Mitosis (in Neurospora, following the usual meiosis (1 and 2), the resulting gametes undergo another round of mitosis, before they are ready for fertilisation)
2. Assume that a true-breeding female with the dominant phenotype is crossed to a true-breeding male with the recessive phenotype (Generation 0). Female offspring are then backcrossed to males with the recessive phenotype (Generation 1). This process is then repeated, with each new generation created by crossing the female offspring from the previous backcross generation to males with the recessive phenotype. If this trait is controlled by a maternal effect gene, in which backcross generation will some of the females used for the backcross have the recessive phenotype? d) 3 ( in the first generation, none of the females will be genotypically or phenotypically of the recessive phenotype; in the second generation, the recessive genotype will appear, but will not show in the phenotype; it is only in the third generation that the recessive phenotype will appear in the female).
3. and 4. in the image attached below.