Complete Dominance
►One
parent is heterozygous for a
trait. The other is homozygous.
What fraction of their offspring
will be heterozygous?
► Pea
plants having wrinkled seeds are
crossed with pea plants having round
seeds. Round is the dominant allele
and the plant with round seeds is
homozygous.
►A
sunflower with a long stem is
crossed with a sunflower with a short
stem. The plant with the long stem is
heterozygous and the plant with the
short stem is homozygous.
►A
mother and a father, both having
brown eyes, have offspring with blue
eyes. Show how this is possible using
Punnett square and ratios.
► Two
black mice when mated produce some
offsrping that are white. Explain with
Punnett square and ratios.
► You
learned how Mendel crossed two plants
of the F1 generation to test flower color.
Pretend that you are Mendel crossing two
plants of the F1 generation for seed color.
Use your notes and your text to do the
Punnett square and ratios for this trait.
► If you produced 8023 plants, approximately
how many plants will have yellow seeds and
how many would have green seeds?
►A
heterozygous black guinea pig is mated
with a homozygous recessive white guinea
pig. Determine the gametes formed by each
parent and work a Punnett square to predict
the genotype and phenotype ratios of the
offspring.
► Pictured
above is an alien who displays all of the
dominant characteristics of its species. I have
given you a chart listing various traits found in
this alien race. Use the information in the chart
to solve the genetics problems that follow.
►A
heterozygous male mates with a pure
yellow female. What is the chance this
couple will produce an orange baby? Check
your answer
► Two
purple-eyed aliens mate. Both aliens
are hybrid for the eye color trait. What is
the chance this couple will produce a baby
with a homozygous recessive
genotype? Check your answer
►A
heterozygous female with 3 body rings
mates with a 5-ringed male. What is the
chance that this couple will have a baby
that looks like its mother? Check your
answer
►A
pure male alien displaying the dominant
body color mates with a female that is
homozygous recessive for this
characteristic. What is the chance that this
couple will have a baby with a hybrid
genotype? Check your answer
►A
male alien with 1 antenna mates with a
female alien who has 2 antennae. The
female is heterozygous for the antenna
trait. What is the chance that this couple
will produce a baby with the recessive
phenotype? Check your answer
► An
alien couple, both of which wear glasses,
are having a baby. The male's genotype is
heterozygous. The female is phenotypically
dominant but does carry the recessive
allele. What is the chance that this couple's
baby will have to wear glasses? Check your
answer
►A
3-ringed female mates with a
homozygous male. The female has been
genetically tested and is carrying both the
dominant and the recessive allele for this
trait. The male displays the recessive
phenotype. What is the chance that this
couple will have a genetically pure baby?
Check your answer
Dihybrid Crosses
► Two
traits for guinea pigs are coat texture
(rough or smooth) and coat color (black or
albino). R=rough; r=smooth; B=black;
b=albino. A heterozygous black/ smooth
coated male is bred with a heterozygous
black/ heterozygous rough coated female.
Use a Punnett square to solve for phenotype
ratios.
►
Two parent pea plants that are
heterozygous for flower color and
heterozygous for pod shape are crossed.
Determine the phenotype ratio for this
cross.
► The
lubber grasshopper is a very large
grasshopper, and is black with red and yellow
stripes. Assume that red stripes are expressed
from the homozygous RR genotype, yellow stripes
from the homozygous rr genotype, and both from
the heterozygous genotype. What will be the
phenotypic ratio of the F1 generation resulting
from a cross of two grasshoppers, both with red
and yellow stripes (red : both : yellow)?
► In
Mendel's experiments, if the gene for tall
(T) plants was incompletely dominant over
the gene for short (t) plants, what would be
the result of crossing two Tt plants?
► Labrador
retrievers demonstrate incomplete
dominance for fur color. Black is
incompletely dominant over yellow. If you
cross to brown labs what are your chances
of producing black labs?
► One
parent has type AB blood. The other
parents has type B blood but is
heterozygous. Determine ratios for blood
type in offspring.
► What
are the chances of two human parents
having a boy? Determine ratios to prove
your answer.