Exam 4 FRQs questions well
answered graded A+ passed
Prediction: 75% - ANS ✔In the tongue sole fish (Hyoglossus similes), sex is determined by a
combination of genetics and environmental temperature. Genetically male fish have two Z
chromosomes (ZZ), and genetically female fish have one Z chromosome and one W
chromosome (ZW). When fish are raised at 22℃, ZZ fish develop into phenotypic males and ZW
fish develop into phenotypic females. However, when fish are raised at 28℃, the Z chromosome
is modified (denoted as Z*). Z*W individuals develop as phenotypic males that are fertile and
can pass on the Z* chromosome to their offspring even when the offspring are raised at 22℃. A
cross between a ZW female and a Z*Z male is shown in the Punnett square below.
ZW
Z* Z*Z Z*W
ZZZZW
Predict the percent of phenotypic males among the F1 offspring of the cross shown in the
Punnett square if the offspring are raised at 22℃.
Identification: Z* W
Z* W
Z Z*Z ZW 2 males, 1 female, 1 dead
W Z*Z WW
Description:
• Fewer offspring will develop/survive.
• 1/4 of the offspring are predicted to die.
• Some of her offspring will have the Z* chromosome/all of her male offspring will have a
Z* chromosome. - ANS ✔In the tongue sole fish (Cynoglossus semilaevis), sex is determined by
a combination of genetics and environmental temperature. Genetically male fish have two Z
chromosomes (ZZ), and genetically female fish have one Z chromosome and one W
, chromosome (ZW). When fish are raised at 22℃, ZZ fish develop into phenotypic males and ZW
fish develop into phenotypic females. However, when fish are raised at 28℃, the Z chromosome
is modified (denoted as Z*). Z*W individuals develop as phenotypic males that are fertile and
can pass on the Z* chromosome to their offspring even when the offspring are raised at 22℃. A
cross between a ZW female and a Z*Z male is shown in the Punnett square below.
ZW
Z* Z*Z Z*W
ZZZZW
At least one Z or Z* chromosome is necessary for survival of the fish. A researcher crossed two
fish and observed a 2:1 ratio of males to females among the offspring. Based on the
information, identify the genotyp
Description: The amino acid substitution changes the shape/structure/function of the protein
Reasoning: The mutation decreases/eliminates gibberellin production. - ANS ✔Gibberellin is the
primary plant hormone that promotes stem elongation. GA 3-beta-hydroxylase (GA3H) is the
enzyme that catalyzes the reaction that converts a precursor of gibberellin to the active form of
gibberellin. A mutation in the GA3H gene results in a short plant phenotype. When a pure-
breeding tall plant is crossed with a pure-breeding short plant, all offspring in the F1 generation
are tall. When the F1 plants are crossed with each other, 75 percent of the plants in the F2
generation are tall and 25 percent of the plants are short.
The wild-type allele encodes a GA3H enzyme with alanine (Ala), a nonpolar amino acid, at
position 229. The mutant allele encodes a GA3H enzyme with a threonine (Thr), a polar amino
acid, at position 229. Describe the effect of the mutation on the enzyme and provide reasoning
to support how this mutation results in a short plant phenotype in homozygous recessive
plants.
Prediction:
• G ↔ A in the first position (of the codon)
• 5′-GCN-3′ ↔ 5′-ACN-3′
answered graded A+ passed
Prediction: 75% - ANS ✔In the tongue sole fish (Hyoglossus similes), sex is determined by a
combination of genetics and environmental temperature. Genetically male fish have two Z
chromosomes (ZZ), and genetically female fish have one Z chromosome and one W
chromosome (ZW). When fish are raised at 22℃, ZZ fish develop into phenotypic males and ZW
fish develop into phenotypic females. However, when fish are raised at 28℃, the Z chromosome
is modified (denoted as Z*). Z*W individuals develop as phenotypic males that are fertile and
can pass on the Z* chromosome to their offspring even when the offspring are raised at 22℃. A
cross between a ZW female and a Z*Z male is shown in the Punnett square below.
ZW
Z* Z*Z Z*W
ZZZZW
Predict the percent of phenotypic males among the F1 offspring of the cross shown in the
Punnett square if the offspring are raised at 22℃.
Identification: Z* W
Z* W
Z Z*Z ZW 2 males, 1 female, 1 dead
W Z*Z WW
Description:
• Fewer offspring will develop/survive.
• 1/4 of the offspring are predicted to die.
• Some of her offspring will have the Z* chromosome/all of her male offspring will have a
Z* chromosome. - ANS ✔In the tongue sole fish (Cynoglossus semilaevis), sex is determined by
a combination of genetics and environmental temperature. Genetically male fish have two Z
chromosomes (ZZ), and genetically female fish have one Z chromosome and one W
, chromosome (ZW). When fish are raised at 22℃, ZZ fish develop into phenotypic males and ZW
fish develop into phenotypic females. However, when fish are raised at 28℃, the Z chromosome
is modified (denoted as Z*). Z*W individuals develop as phenotypic males that are fertile and
can pass on the Z* chromosome to their offspring even when the offspring are raised at 22℃. A
cross between a ZW female and a Z*Z male is shown in the Punnett square below.
ZW
Z* Z*Z Z*W
ZZZZW
At least one Z or Z* chromosome is necessary for survival of the fish. A researcher crossed two
fish and observed a 2:1 ratio of males to females among the offspring. Based on the
information, identify the genotyp
Description: The amino acid substitution changes the shape/structure/function of the protein
Reasoning: The mutation decreases/eliminates gibberellin production. - ANS ✔Gibberellin is the
primary plant hormone that promotes stem elongation. GA 3-beta-hydroxylase (GA3H) is the
enzyme that catalyzes the reaction that converts a precursor of gibberellin to the active form of
gibberellin. A mutation in the GA3H gene results in a short plant phenotype. When a pure-
breeding tall plant is crossed with a pure-breeding short plant, all offspring in the F1 generation
are tall. When the F1 plants are crossed with each other, 75 percent of the plants in the F2
generation are tall and 25 percent of the plants are short.
The wild-type allele encodes a GA3H enzyme with alanine (Ala), a nonpolar amino acid, at
position 229. The mutant allele encodes a GA3H enzyme with a threonine (Thr), a polar amino
acid, at position 229. Describe the effect of the mutation on the enzyme and provide reasoning
to support how this mutation results in a short plant phenotype in homozygous recessive
plants.
Prediction:
• G ↔ A in the first position (of the codon)
• 5′-GCN-3′ ↔ 5′-ACN-3′
