ATTACK OF THE “MEND-ALIENS”

In MendAliens, normal head top is dominant to Bart head top, in which the top of the head is jagged. Suppose a MendAlien homozygous for normal head shape is crossed with one homozygous for Bart head shape.

a. What are the genotypes of the two parents?

For each of the following, give the genotype(s) and phenotypes(s) and their proportions:

b. the F₁ generation
c. the F₂ generation
d. the offspring of a cross of an F₁ individual to a true-breeding normal-head-topped individual
e. the offspring of a cross of an F₁ individual to a Bart-head-topped individual

ONE EYED PURPLE PEOPLE EATERS

This problem involves MendAliens with one eye instead of the normal two and a purple skin color instead of the normal green. The following crosses were done:

a. What is the mechanism of inheritance for the one-eye (Cyclops) trait? Explain your answer.

b. What is the mechanism of inheritance for the purple-color trait? Explain your answer.

c. Considering the two traits together, what can you say about how they are inherited?

d. Assign appropriate allele symbols, and diagram the cross through to the F₂ generation.

e. Give the appearances and their proportions in the offspring of a cross of an F₁ individual to a one-eye, purple individual.

http://www.phschool.com/science/biology_place/biocoach/inheritance/intro.html

POINDEXTER

Problem Statement
The pointed-ear trait in MendAliens is caused by an X-linked recessive mutant allele.

a. A female MendAlien, Marge, with no ears (the normal condition) and whose male parent had pointed ears pairs with a male MendAlien with no ears and whose male parent also had pointed ears. The pointed ears phenotype looks like this:



Using e for the pointed-ears allele and E for the normal no-ear allele, diagram the cross, and give the proportions of the phenotypes in the offspring that will have ears. (Give your answer separately for males and females.)

b. Assume, instead, that the female MendAlien, in part a, pairs with a male MendAlien with pointed ears as follows:



Diagram the cross, and give the proportion of the phenotypes in the offspring. (Give your answer separately for males and females.)

http://www.phschool.com/science/biology_place/biocoach/inheritance/intro.html

PROBLEM #4

Problem Statement
To investigate the genetics of the round-head trait, a cross between two round-headed MendAliens was made with the following results:

a. What is the simplest explanation for the inheritance of these head shapes?

b. Give the genotypes of the parents and the progeny.

c. What offspring would you expect from a cross between a MendAlien with a round head and a MendAlien with a disk head?

http://www.phschool.com/science/biology_place/biocoach/inheritance/intro.html

PROBLEM “X”

In MendAliens, orange eyes (o) is recessive to the normal black eyes, and zebra striping (z) is recessive to no striping. Homozygous black-eyed, nonstriped MendAliens were crossed with orange-eyed, zebra-striped MendAliens. The F₁ were testcrossed to orange-eyed, zebra-striped individuals to produce progeny as shown below.

What is the map distance between the genes for eye color and striping?

http://www.phschool.com/science/biology_place/biocoach/inheritance/intro.html