Name: Katie Letson______________________________
Date: 8/4/2022______________________________
BIO 120L Module Six Lab Report: The Biology Project
The Biology Project Mendelian Genetics
Go to the Biology Project: Mendelian Genetics website. Complete two of the problem sets: Monohybrid
Cross and Dihybrid Cross. Use these questions as practice. Take notes and then answer the following
questions.
1) If you crossed a true-breeding (homozygous) plant with pink flowers and a true-breeding
(homozygous) plant with white flowers and all resulting offspring had pink flowers, which color
trait would you consider to be recessive? Why?
The parent plants being both homozygous white(ww) and the other one determining homozygous
pink(WW) will make a heterozygous pink(Ww) offspring. The flowers will be pink because it is dominant
over white but it still carries the white flower recessive gene.
2) If your mother had a widow’s peak, which can be homozygous dominant (WW) or heterozygous
(Ww), and your father had a straight hairline, which is homozygous recessive (ww), what
percentage of their children would have a straight hairline? Consider both genotype possibilities
for the mother. Explain your answer.
Only the offspring with (ww) would have a straight hairline. If (W) is the dominant allele.
Then (w) is the recessive allele. This would mean only offspring with (WW) or (Ww) genotype
would have a widow's peak. The genotype for both parents must be considered when
determining the probability of inheritance of any dominant trait. 0% would have a straight
hairline. 100% of the offspring would have heterozygous (Ww) a widows peak.
3) Green seeds are considered a recessive trait (yy) in pea plants. If Mendel wanted to breed only
yellow-seeded pea plants, would he get the outcome he was looking for by removing all of the
green-seeded pea plants? Why or why not?
No, because green seeds are considered a recessive trait (yy) in a pea plant and are expressed only
in homozygous condition(yy). Even if he removed all the green seeds, there is a high possibility of some
yellow seeds being heterozygous (Yy). These plants would pass the recessive allele (y) to the offspring
and have green seeds.
4) In an experiment, if all the alleles you were studying had a clear dominant/recessive
relationship, what would you assume the resulting phenotypic ratio would be from a dihybrid
cross?
The resulting phenotypic ratio would be 9:3:3:1.
Date: 8/4/2022______________________________
BIO 120L Module Six Lab Report: The Biology Project
The Biology Project Mendelian Genetics
Go to the Biology Project: Mendelian Genetics website. Complete two of the problem sets: Monohybrid
Cross and Dihybrid Cross. Use these questions as practice. Take notes and then answer the following
questions.
1) If you crossed a true-breeding (homozygous) plant with pink flowers and a true-breeding
(homozygous) plant with white flowers and all resulting offspring had pink flowers, which color
trait would you consider to be recessive? Why?
The parent plants being both homozygous white(ww) and the other one determining homozygous
pink(WW) will make a heterozygous pink(Ww) offspring. The flowers will be pink because it is dominant
over white but it still carries the white flower recessive gene.
2) If your mother had a widow’s peak, which can be homozygous dominant (WW) or heterozygous
(Ww), and your father had a straight hairline, which is homozygous recessive (ww), what
percentage of their children would have a straight hairline? Consider both genotype possibilities
for the mother. Explain your answer.
Only the offspring with (ww) would have a straight hairline. If (W) is the dominant allele.
Then (w) is the recessive allele. This would mean only offspring with (WW) or (Ww) genotype
would have a widow's peak. The genotype for both parents must be considered when
determining the probability of inheritance of any dominant trait. 0% would have a straight
hairline. 100% of the offspring would have heterozygous (Ww) a widows peak.
3) Green seeds are considered a recessive trait (yy) in pea plants. If Mendel wanted to breed only
yellow-seeded pea plants, would he get the outcome he was looking for by removing all of the
green-seeded pea plants? Why or why not?
No, because green seeds are considered a recessive trait (yy) in a pea plant and are expressed only
in homozygous condition(yy). Even if he removed all the green seeds, there is a high possibility of some
yellow seeds being heterozygous (Yy). These plants would pass the recessive allele (y) to the offspring
and have green seeds.
4) In an experiment, if all the alleles you were studying had a clear dominant/recessive
relationship, what would you assume the resulting phenotypic ratio would be from a dihybrid
cross?
The resulting phenotypic ratio would be 9:3:3:1.
