More Mendelian Principles
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Lilli Howard
BIOL/GEN 313
Dr. Vollbrecht
03/04/14
1. How might you determine whether a particular trait is due to cytoplasmic inheritance or
to genetic maternal effect?
2. A women has blood-type A M. She has a child with blood-type AB MN. Which of the
following blood types could not be that of the child’s father? Explain.
a. O
N
b. AB
MN
c. B
MN
d. A
N
e. AB
M
3. In chickens, comb shape is determined by alleles at two loci (R and P). A walnut comb is
produced when at least one dominant allele R is present at one locus and at least one
dominant allele P is present at a second locus (genotype R_ P_). A rose comb is produced
when at least one dominant allele is present at the first locus and two recessive alleles are
present at the second locus (genotype R_ pp). A pea comb is produced when two
recessive alleles are present at the first locus and at least one dominant allele is present at
the second (genotype rr P_). If two recessive alleles are present at the first and at the
second locus (rr pp), a single comb is produced. Progeny with what types of combs and in
what proportions will result from the following crosses?
a. RR PP × rr pp
b. Rr Pp × rr pp
c. Rr Pp × Rr Pp
d. Rr pp × Rr pp
e. Rr pp × rr Pp
f. Rr pp × rr pp
1060 Hixson-Lied Student Success Center  515-294-6624  sistaff@iastate.edu  http://www.si.iastate.edu
4. A dog breeder liked yellow and brown Labrador retrievers. In an attempt to produce
yellow and brown puppies, he bought a yellow Labrador male and a brown Labrador
female and mated them. Unfortunately, all the puppies produced in this cross were black.
All black labs must carry at least one B allele and one E allele. Brown dogs are
homozygous bb and have at least one E allele. Yellow dogs are homozygous ee.
a. Explain this result.
b. How might the breeder go about producing yellow and brown Labradors?
5. A summer squash plant that produces disc-shaped fruit is crossed with a plant that
produces long fruit. All the F1 have disc-shaped fruit. When the F1are intercrossed, F2
progeny are produced in the following ratio: 9/16 disc-shaped fruit: 6/16 spherical fruit:
1/16 long fruit.
Give the genotypes of the F2 progeny.
6. You have crossed a mutant mouse with a normal mouse. The offspring all have a mutant
phenotype. How could you distinguish between whether this is:
a. A dominant allele?
b. A cytoplasmic trait?
c. An allele showing a maternal effect?
d. Imprinted gene?
1060 Hixson-Lied Student Success Center  515-294-6624  sistaff@iastate.edu  http://www.si.iastate.edu