For the cross AABBCCDd × AAbbCcDd, what is the probability that an offspring will be AABbCcDd? A. 1⁄16 B. 1⁄8 C. 1⁄4 D. 3⁄8 E. 1⁄2
2. What fraction of the offspring of the cross AaBb × AaBb would show the dominant
phenotypes for both genes?
Suppose unattached earlobes are a dominant trait. Phil and Maggie both have
unattached earlobes but their daughter, Celia, does not. If Phil and Maggie have a second
child, what is the probability that it will have attached earlobes?
d. 3⁄4 e. 1
The cross AaBb × AaBb is an example of a _______ cross; the results of such crosses
led Mendel to propose what we now call the law of _______.
a. self-; segregation of genes
b. dihybrid; segregation of genes
c. dihybrid; independent assortment
d. test; segregation of genes
e. test; independent assortment
C. Dihybrid; independent assortment
In a test cross, peas of an unknown genotype are crossed with peas of a known genotype. In this example, smooth peas are the unknown and wrinkled peas are known (rr). If half of the offspring from that cross are smooth and half are wrinkled, what
is the genotype of the unknown plant?
a. Incomplete dominance
b. Homozygous dominant: RR
c. Homozygous recessive: rr d. Heterozygous: Rr e. The genotype cannot be determined from the information given.
D. Heterozygous: Rr
. The 9:3:3:1 ratio is obtained
a. through a dihybrid cross in which the genes are linked on the same chromosome.
b. through a dihybrid cross in which the genes are on different chromosomes.
c. when crossing over occurs.
d. in a test cross.
e. None of the above
B. Through a dihybrid cross in which the genes are on different chromosomes.