dogs, wire hair (S) is dominant to smooth (s).
In a cross of a homozygous wire-haired dog
with a smooth-haired dog, what will be the phenotype
of the F1 generation?
What would be the genotype?
What would be the ratio
of wire-haired to smooth-haired dogs in the F2
2. Woodrats are medium sized rodents with lots of interesting behaviors. You may know of them as packrats. Let's assume that the trait of bringing home shiny objects (H) is controlled by a single locus gene and is dominant to the trait of carrying home only dull objects (h). Suppose two heterozygous individuals are crossed. How many of each genotype would be expected if only 4 offspring were produced?
How many of each phenotype?
|Brings home shiny objects:|
|Brings home dull objects:|
cacti are very tall cylindrical plants that usually have two L-shaped arms,
one on each side. Suppose you lived in southern Arizona where the Saguaro
cactus is common and you happen to have one growing in your yard. Your
Saguaro has two arms but one is longer than the other. Now, assume that
arm length in these cacti are controlled by a single gene
with arms of the same length (A) being
to arms of different lengths. What is the genotype
of your cactus?
Could one of the parents of your cactus have had a phenotype
with arms the same length?
If so, what would have been the genotype
of that parent?
Suppose you cross your cactus with that of your neighbor
which has arms of the same length. Your great grandchildren (it takes a
Saguaro cactus a long time to mature) find that half of the resulting offspring
have arms the same length and half have arms of different lengths. What
was the genotype of your neighbor's cactus?
common grackle is a species of robin-sized blackbirds that are fairly common
(hence the name) over most of the United States. Suppose that long tails
(L) were dominant to short tails in these birds.
A female short-tailed grackle mates with a male long-tailed grackle who
had one parent with a long tail and one parent with a short tail. What
is the male's genotype?
How many of each genotype
will be found in the F1 generation
(assume 4 offspring)?
How many of each phenotype
will be found in the F1 generation?
5. The ability to curl your tongue up on the sides (T, tongue rolling) is dominant to not being able to roll your tongue. A woman who can roll her tongue marries a man who cannot. Their first child has his father's phenotype. What are the genotypes of the mother, father, and child?
What is the probability that a second child won't be a
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