Download Monohybrid Crosses

Monohybrid Crosses
1. In Orks, the allele for Blue skin (B) is dominant over the allele for red skin (b). Edward Ork is
homozygous dominant for blue skin. Olivia Ork is heterozygous for blue skin. Cross Olivia
and Edward below. Provide all genotypes and phenotypes that are possible in their offspring
with probabilities.
________X________
Key:
2. a. In pea plants, the allele for Axial flower position (A) is dominant over the
allele for top flower position (a). Cross a homozygous dominant plant with a homozygous
recessive plant. Provide all genotypes and phenotypes that are possible in their offspring
with probabilities.
________X________
2.
Key:
b. Cross two members of the first filial generation above. Provide all genotypes and
phenotypes that are possible in their offspring with probabilities.
________X________
Key:
3. In pea plants, the allele for Yellow seed color (Y) is dominant to the allele for green seed
color (y). Cross a heterozygous plant with a homozygous recessive plant. Provide all
genotypes and phenotypes that are possible in their offspring with probabilities.
________X________
Key:
4. In pea plants, the allele for a tall plant (T) is dominant over the allele for a short plant (t). Cross
a homozygous dominant plant with a heterozygous plant. What is the probability of having tall
offspring produced by this cross?
________X________
Key:
5. In guinea pigs, the allele for short hair (S) is dominant over the allele for long hair (s). Cross
two heterozygous guinea pigs. Would these two guinea pigs produce offspring that would be a
good phenotypic selection to start a guinea pig business?
________X________
Key:
6. In Blebs, the allele for Fur (F) is dominant over the allele for Baldness (f). Cross a
heterozygous Bleb with a Bleb that is pure for baldness. What is the probability of producing
baby Blebs that are pure for baldness?
________X________
Key:
Dihybrid Crosses
7. In pea plants, the allele for a tall plant (T) is dominant over the allele for a short plant (t). Also,
the allele for Green pod color (G) over the allele for yellow pod color (g). Cross two plants that
are heterozygous for both traits. What phenotypes will result in the offspring from this cross?
Provide probabilities.
_____________X_____________
8. In humans, the allele for Free earlobes (F) is dominant over the allele for Attached earlobes (f).
Also, the allele for a Round nose (R) is dominant over the allele for a Pointed nose (r). Bob is
heterozygous for Free earlobes and homozygous recessive for a Pointed nose. Lucy is
homozygous dominant for both traits. Cross Bob and Lucy and provide probabilities of
phenotypes for their children.
_____________X_____________
9. In pea plants, the allele for Round seeds (R) is dominant over the allele for wrinkled seeds (r).
Also, the allele for Axial flower position (A) is dominant over the allele for top flower position
(a). Cross a plant that is heterozygous for both traits with a plant that is homozygous recessive
for seed texture and heterozygous for flower position. What phenotypes will result in the
offspring from this cross? Provide probabilities.
_____________X_____________
10. a. Mr. and Mrs. Ork want to have more children. In Orks, the allele for Blue hair (B) is
dominant over the allele for green hair (b) and the allele for egg head (E) is dominant over the
allele for square head (e). Mr. Ork is pure for Blue hair and square head. Mrs. Ork is pure for
green hair and egg head. What phenotypes will be present in the Ork children? Provide
probabilities.
_____________X_____________
10. b. Two of the Ork children are going to mate. Give the phenotypic ratio of this union.
_____________X_____________
11. In Sallies, the allele for High-pitched voices (H) is dominant over the allele for low-pitched
voices (h). Also, the allele for Long toes (L) is dominant over the allele for short toes (l).
Cross a Sally that is homozygous recessive for both traits with a Sally that is homozygous
dominant for voice and homozygous recessive for toes. What phenotypes will result in the
offspring from this cross? Provide probabilities.
_____________X_____________
12. In pea plants, the allele for purple flowers (P) is dominant over the allele for white flowers (p).
Also, the allele for Tall plants (T) is dominant over the allele for short plants (t). Cross a plant
that is heterozygous for both traits with a plant that is heterozygous for flower color and
homozygous dominant for height. What phenotypes will result in the offspring from this cross?
Provide probabilities.
_____________X_____________