Understanding Dominant/Recessive - High School Biology
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The trait "tall" is dominant (T) while "short" is recessive (t). If two parents are both heterozygous for the trait and have a child, what is the probability that the child would be phenotypically short?
The trait "tall" is dominant (T) while "short" is recessive (t). If two parents are both heterozygous for the trait and have a child, what is the probability that the child would be phenotypically short?
The problem can be solved using the following Punnett square. Since short is recessive, the only genotype that will result in a short appearance is tt. tt occurs one time on the Punnett square, out of four possible combinations; therefore, there is a 1-in-4 chance of giving birth to a short child, or 25%.
The problem can be solved using the following Punnett square. Since short is recessive, the only genotype that will result in a short appearance is tt. tt occurs one time on the Punnett square, out of four possible combinations; therefore, there is a 1-in-4 chance of giving birth to a short child, or 25%.
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Two pure breeding plants are crossed. One has purple flowers and the other has white flowers. The first generation is composed of only purple flowers. When the first generation is self pollinated, there is a 3 to 1 ratio of purple to white flowers in the second generation.
What percentage of the second generation has a heterozygous genotype?
Two pure breeding plants are crossed. One has purple flowers and the other has white flowers. The first generation is composed of only purple flowers. When the first generation is self pollinated, there is a 3 to 1 ratio of purple to white flowers in the second generation.
What percentage of the second generation has a heterozygous genotype?
Since the parents are pure breeding, we can designate the purple flowers as PP and the white flowers as pp. Upon breeding, there will only be one possible plant created, which has a genotype of Pp.
PP x pp
Offspring: all offspring are Pp and will display the dominant phenotype (purple)
Upon self fertilization, there will be three genotypes in the second generation: PP, Pp, and pp. A punnet square will show that 50% of the second generation will be homozygous and 50% of the second generation will be heterozygous for the color trait.
Pp x Pp
Offspring: one PP, two Pp, one pp. PP and pp are homozygous, and the two Pp are heterozygous.
Since the parents are pure breeding, we can designate the purple flowers as PP and the white flowers as pp. Upon breeding, there will only be one possible plant created, which has a genotype of Pp.
PP x pp
Offspring: all offspring are Pp and will display the dominant phenotype (purple)
Upon self fertilization, there will be three genotypes in the second generation: PP, Pp, and pp. A punnet square will show that 50% of the second generation will be homozygous and 50% of the second generation will be heterozygous for the color trait.
Pp x Pp
Offspring: one PP, two Pp, one pp. PP and pp are homozygous, and the two Pp are heterozygous.
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Two pure breeding plants are crossed. One has purple flowers and the other has white flowers. The first generation is composed of only purple flowers. When the first generation is self pollinated, there is a 3 to 1 ratio of purple to white flowers in the second generation.
Two flowers in the second generation are crossed. Both are purple, but one is homozygous for the color and the other is heterozygous. What percentage of their offspring will be purple?
Two pure breeding plants are crossed. One has purple flowers and the other has white flowers. The first generation is composed of only purple flowers. When the first generation is self pollinated, there is a 3 to 1 ratio of purple to white flowers in the second generation.
Two flowers in the second generation are crossed. Both are purple, but one is homozygous for the color and the other is heterozygous. What percentage of their offspring will be purple?
The genotypes for the two plants in question can be written as PP for the homozygous dominant plant, and Pp for the heterozygous plant. Remember that a white flower can only be created if it receives two recessive alleles, one from each parent. The homozygous dominant plant can only contribute a dominant allele, so every offspring will have a dominant allele. As a result, every flower will be purple when these two plants are crossed.
PP x Pp
Offspring: Half PP and half Pp. All carry a dominant allele, and will display the dominant phenotype.
The genotypes for the two plants in question can be written as PP for the homozygous dominant plant, and Pp for the heterozygous plant. Remember that a white flower can only be created if it receives two recessive alleles, one from each parent. The homozygous dominant plant can only contribute a dominant allele, so every offspring will have a dominant allele. As a result, every flower will be purple when these two plants are crossed.
PP x Pp
Offspring: Half PP and half Pp. All carry a dominant allele, and will display the dominant phenotype.
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Red and white are two alleles of a single gene for flower color. A red plant and a white plant are crossed. Some offspring have red flowers and some offspring have white flowers. Which of the following could not be true?
Red and white are two alleles of a single gene for flower color. A red plant and a white plant are crossed. Some offspring have red flowers and some offspring have white flowers. Which of the following could not be true?
If either parent were homozygous dominant, all offspring would exhibit the dominant phenotype and the second phenotype would not be expressed.
Homozygous parent cross: RR x r_
Offspring: all offspring inherit a dominant R allele and will express the dominant phenotype.
If two heterozygotes are crossed, all three genotypes will be expressed, so all possible phenotypes will be expressed.
Both heterozygous: Rr x Rr
Offspring: 1 RR, 2 Rr, 1 rr with both dominant and recessive phenotypes expressed in a 3:1 ratio.
If one heterozygote and one homozygote are crossed the offspring will show only two genotypes, but both possible phenotypes.
One heterozygote: Rr x rr
Offspring: half Rr and half rr, with half showing dominant phenotype and half showing recessive phenotype.
The second and third examples give rise to both colors of offspring, regardless of which allele is dominant. The first example only shows the dominant phenotype, can cannot be possible for this question.
If either parent were homozygous dominant, all offspring would exhibit the dominant phenotype and the second phenotype would not be expressed.
Homozygous parent cross: RR x r_
Offspring: all offspring inherit a dominant R allele and will express the dominant phenotype.
If two heterozygotes are crossed, all three genotypes will be expressed, so all possible phenotypes will be expressed.
Both heterozygous: Rr x Rr
Offspring: 1 RR, 2 Rr, 1 rr with both dominant and recessive phenotypes expressed in a 3:1 ratio.
If one heterozygote and one homozygote are crossed the offspring will show only two genotypes, but both possible phenotypes.
One heterozygote: Rr x rr
Offspring: half Rr and half rr, with half showing dominant phenotype and half showing recessive phenotype.
The second and third examples give rise to both colors of offspring, regardless of which allele is dominant. The first example only shows the dominant phenotype, can cannot be possible for this question.
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Consider two traits in pea plants that exhibit complete dominance. Smooth peas are dominant to wrinkled peas, and purple flowers are dominant to white flowers.
A pure breeding plant with purple flowers and wrinkled peas is crossed with a pure breeding plant with white flowers and smooth peas. The first generation is self-pollinated to produce the second generation.
What fraction of the second generation will have purple flowers with wrinkled peas?
Consider two traits in pea plants that exhibit complete dominance. Smooth peas are dominant to wrinkled peas, and purple flowers are dominant to white flowers.
A pure breeding plant with purple flowers and wrinkled peas is crossed with a pure breeding plant with white flowers and smooth peas. The first generation is self-pollinated to produce the second generation.
What fraction of the second generation will have purple flowers with wrinkled peas?
When dealing with two traits, it helps to approach each trait separately. The question asks for the fraction of plants in the second generation that have purple flowers and wrinkled peas.
First, we will look at the first generation. The parents are both pure breeding, meaning they are homozygous for each trait. One is purple (dominant) and wrinkled (recessive), while the other is white (recessive) and round (dominant). The result will be dihybrid offspring.
Parent cross: PPrr x ppRR
Offspring: All offspring will be PpRr and exhibit both dominant phenotypes (purple and round).
Now we will look at the first generation self-cross for each trait.
First generation: PpRr x PpRr
Offspring for color: 1 PP, 2 Pp, 1 pp; 3 purple and 1 white.
Offspring for seeds: 1 RR, 2 Rr, 1 rr; 3 round and 1 wrinkled.
We can see that three-fourths of the offspring will be purple, since they carry the dominant allele, and one-fourth of the offspring will be wrinkled, since only one of four will carry two recessive alleles.
Since we are looking for plants that have both of these traits, we multiply these two probabilities together.
In other words, 
of the second generation will have purple flowers and wrinkled peas.
When dealing with two traits, it helps to approach each trait separately. The question asks for the fraction of plants in the second generation that have purple flowers and wrinkled peas.
First, we will look at the first generation. The parents are both pure breeding, meaning they are homozygous for each trait. One is purple (dominant) and wrinkled (recessive), while the other is white (recessive) and round (dominant). The result will be dihybrid offspring.
Parent cross: PPrr x ppRR
Offspring: All offspring will be PpRr and exhibit both dominant phenotypes (purple and round).
Now we will look at the first generation self-cross for each trait.
First generation: PpRr x PpRr
Offspring for color: 1 PP, 2 Pp, 1 pp; 3 purple and 1 white.
Offspring for seeds: 1 RR, 2 Rr, 1 rr; 3 round and 1 wrinkled.
We can see that three-fourths of the offspring will be purple, since they carry the dominant allele, and one-fourth of the offspring will be wrinkled, since only one of four will carry two recessive alleles.
Since we are looking for plants that have both of these traits, we multiply these two probabilities together.
In other words,
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Consider two traits in pea plants that exhibit complete dominance. Smooth peas are dominant to wrinkled peas, and purple flowers are dominant to white flowers.
A pure breeding plant with purple flowers and wrinkled peas is crossed with a pure breeding plant with white flowers and smooth peas. The first generation is self-pollinated to produce the second generation.
What fraction of the second generation will be heterozygous for both traits?
Consider two traits in pea plants that exhibit complete dominance. Smooth peas are dominant to wrinkled peas, and purple flowers are dominant to white flowers.
A pure breeding plant with purple flowers and wrinkled peas is crossed with a pure breeding plant with white flowers and smooth peas. The first generation is self-pollinated to produce the second generation.
What fraction of the second generation will be heterozygous for both traits?
When dealing with two traits, it helps to approach each trait separately. The question asks for the fraction of plants in the second generation that are heterozygous for both traits.
First, we will look at the first generation. The parents are both pure breeding, meaning they are homozygous for each trait. One is purple (dominant) and wrinkled (recessive), while the other is white (recessive) and round (dominant). The result will be dihybrid offspring.
Parent cross: PPrr x ppRR
Offspring: All offspring will be PpRr and exhibit both dominant phenotypes (purple and round).
Now we will look at the first generation self-cross for each trait.
First generation: PpRr x PpRr
Offspring for color: 1 PP, 2 Pp, 1 pp; 3 purple and 1 white.
Offspring for seeds: 1 RR, 2 Rr, 1 rr; 3 round and 1 wrinkled.
We can see that half of the offspring will be heterozygous for color, and half of the offspring will be heterozygous for seed shape.
Since we are looking for plants that have both of these traits, we multiply these two probabilities together.
When dealing with two traits, it helps to approach each trait separately. The question asks for the fraction of plants in the second generation that are heterozygous for both traits.
First, we will look at the first generation. The parents are both pure breeding, meaning they are homozygous for each trait. One is purple (dominant) and wrinkled (recessive), while the other is white (recessive) and round (dominant). The result will be dihybrid offspring.
Parent cross: PPrr x ppRR
Offspring: All offspring will be PpRr and exhibit both dominant phenotypes (purple and round).
Now we will look at the first generation self-cross for each trait.
First generation: PpRr x PpRr
Offspring for color: 1 PP, 2 Pp, 1 pp; 3 purple and 1 white.
Offspring for seeds: 1 RR, 2 Rr, 1 rr; 3 round and 1 wrinkled.
We can see that half of the offspring will be heterozygous for color, and half of the offspring will be heterozygous for seed shape.
Since we are looking for plants that have both of these traits, we multiply these two probabilities together.
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Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If these mice are crossed, what is the phenotypic ratio of the resulting offspring?
Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If these mice are crossed, what is the phenotypic ratio of the resulting offspring?
When crossing organisms that are heterozygous for two traits, the result is a dihybrid cross.
AaBb x AaBb
Possible offspring: 1 AABB, 1 aaBB, 1 AAbb, 1 aabb, 2 Aabb, 2 aaBb, 2 AaBB, 2 AABb, 4 AaBb
The phenotypic ratio of a heterozygous dihybrid cross for autosomal (none-sex-linked) traits is always 9:3:3:1. Nine offspring will show both dominant traits (AABB, AaBB, AABb, AaBb). Three offspring will show dominance for one trait and recessiveness for the other (Aabb, AAbb) and three offspring will show the reciprocal (aaBb, aaBB). Only one offspring will be recessive for both traits (aabb). For this cross, nine mice will have black fur and brown eyes, three will have black fur and blue eyes, three will have brown fur and brown eyes, and one will have brown fur and blue eyes.
When crossing organisms that are heterozygous for two traits, the result is a dihybrid cross.
AaBb x AaBb
Possible offspring: 1 AABB, 1 aaBB, 1 AAbb, 1 aabb, 2 Aabb, 2 aaBb, 2 AaBB, 2 AABb, 4 AaBb
The phenotypic ratio of a heterozygous dihybrid cross for autosomal (none-sex-linked) traits is always 9:3:3:1. Nine offspring will show both dominant traits (AABB, AaBB, AABb, AaBb). Three offspring will show dominance for one trait and recessiveness for the other (Aabb, AAbb) and three offspring will show the reciprocal (aaBb, aaBB). Only one offspring will be recessive for both traits (aabb). For this cross, nine mice will have black fur and brown eyes, three will have black fur and blue eyes, three will have brown fur and brown eyes, and one will have brown fur and blue eyes.
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Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If these mice are crossed, what fraction of the offspring will have the genotype Aabb?
Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If these mice are crossed, what fraction of the offspring will have the genotype Aabb?
When crossing organisms that are heterozygous for two traits, the result is a dihybrid cross.
AaBb x AaBb
Possible offspring: 1 AABB, 1 aaBB, 1 AAbb, 1 aabb, 2 Aabb, 2 aaBb, 2 AaBB, 2 AABb, 4 AaBb
The phenotypic ratio of a heterozygous dihybrid cross for autosomal (none-sex-linked) traits is always 9:3:3:1. The genotype in this question, Aabb, corresponds to black fur and blue eyes. Two mice out of every sixteen will have this genotype.
When crossing organisms that are heterozygous for two traits, the result is a dihybrid cross.
AaBb x AaBb
Possible offspring: 1 AABB, 1 aaBB, 1 AAbb, 1 aabb, 2 Aabb, 2 aaBb, 2 AaBB, 2 AABb, 4 AaBb
The phenotypic ratio of a heterozygous dihybrid cross for autosomal (none-sex-linked) traits is always 9:3:3:1. The genotype in this question, Aabb, corresponds to black fur and blue eyes. Two mice out of every sixteen will have this genotype.
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Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If these mice are crossed, what fraction of offspring will have the genotype AaBb?
Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If these mice are crossed, what fraction of offspring will have the genotype AaBb?
When crossing organisms that are heterozygous for two traits, the result is a dihybrid cross.
AaBb x AaBb
Possible offspring: 1 AABB, 1 aaBB, 1 AAbb, 1 aabb, 2 Aabb, 2 aaBb, 2 AaBB, 2 AABb, 4 AaBb
The phenotypic ratio of a heterozygous dihybrid cross for autosomal (none-sex-linked) traits is always 9:3:3:1. The genotype in this question, AaBb, corresponds to black fur and brown eyes. Four mice out of every sixteen will have this genotype.
When crossing organisms that are heterozygous for two traits, the result is a dihybrid cross.
AaBb x AaBb
Possible offspring: 1 AABB, 1 aaBB, 1 AAbb, 1 aabb, 2 Aabb, 2 aaBb, 2 AaBB, 2 AABb, 4 AaBb
The phenotypic ratio of a heterozygous dihybrid cross for autosomal (none-sex-linked) traits is always 9:3:3:1. The genotype in this question, AaBb, corresponds to black fur and brown eyes. Four mice out of every sixteen will have this genotype.
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Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If these mice are crossed, what fraction of offspring can be expected to have blue eyes?
Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If these mice are crossed, what fraction of offspring can be expected to have blue eyes?
When crossing organisms that are heterozygous for two traits, the result is a dihybrid cross.
AaBb x AaBb
Possible offspring: 1 AABB, 1 aaBB, 1 AAbb, 1 aabb, 2 Aabb, 2 aaBb, 2 AaBB, 2 AABb, 4 AaBb
The phenotypic ratio of a heterozygous dihybrid cross for autosomal (none-sex-linked) traits is always 9:3:3:1. Nine offspring will show both dominant traits (AABB, AaBB, AABb, AaBb). Three offspring will show dominance for one trait and recessiveness for the other (Aabb, AAbb) and three offspring will show the reciprocal (aaBb, aaBB). Only one offspring will be recessive for both traits (aabb). For this cross, nine mice will have black fur and brown eyes, three will have black fur and blue eyes, three will have brown fur and brown eyes, and one will have brown fur and blue eyes. A total of four mice will carry bb and be recessive for eye color.
When crossing organisms that are heterozygous for two traits, the result is a dihybrid cross.
AaBb x AaBb
Possible offspring: 1 AABB, 1 aaBB, 1 AAbb, 1 aabb, 2 Aabb, 2 aaBb, 2 AaBB, 2 AABb, 4 AaBb
The phenotypic ratio of a heterozygous dihybrid cross for autosomal (none-sex-linked) traits is always 9:3:3:1. Nine offspring will show both dominant traits (AABB, AaBB, AABb, AaBb). Three offspring will show dominance for one trait and recessiveness for the other (Aabb, AAbb) and three offspring will show the reciprocal (aaBb, aaBB). Only one offspring will be recessive for both traits (aabb). For this cross, nine mice will have black fur and brown eyes, three will have black fur and blue eyes, three will have brown fur and brown eyes, and one will have brown fur and blue eyes. A total of four mice will carry bb and be recessive for eye color.
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Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If these mice are crossed, what fraction of offspring can be expected to have black fur?
Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If these mice are crossed, what fraction of offspring can be expected to have black fur?
When crossing organisms that are heterozygous for two traits, the result is a dihybrid cross.
AaBb x AaBb
Possible offspring: 1 AABB, 1 aaBB, 1 AAbb, 1 aabb, 2 Aabb, 2 aaBb, 2 AaBB, 2 AABb, 4 AaBb
The phenotypic ratio of a heterozygous dihybrid cross for autosomal (none-sex-linked) traits is always 9:3:3:1. Nine offspring will show both dominant traits (AABB, AaBB, AABb, AaBb). Three offspring will show dominance for one trait and recessiveness for the other (Aabb, AAbb) and three offspring will show the reciprocal (aaBb, aaBB). Only one offspring will be recessive for both traits (aabb). For this cross, nine mice will have black fur and brown eyes, three will have black fur and blue eyes, three will have brown fur and brown eyes, and one will have brown fur and blue eyes. A total of twelve mice will carry an A allele and be dominant for fur color.
When crossing organisms that are heterozygous for two traits, the result is a dihybrid cross.
AaBb x AaBb
Possible offspring: 1 AABB, 1 aaBB, 1 AAbb, 1 aabb, 2 Aabb, 2 aaBb, 2 AaBB, 2 AABb, 4 AaBb
The phenotypic ratio of a heterozygous dihybrid cross for autosomal (none-sex-linked) traits is always 9:3:3:1. Nine offspring will show both dominant traits (AABB, AaBB, AABb, AaBb). Three offspring will show dominance for one trait and recessiveness for the other (Aabb, AAbb) and three offspring will show the reciprocal (aaBb, aaBB). Only one offspring will be recessive for both traits (aabb). For this cross, nine mice will have black fur and brown eyes, three will have black fur and blue eyes, three will have brown fur and brown eyes, and one will have brown fur and blue eyes. A total of twelve mice will carry an A allele and be dominant for fur color.
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Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If one of the offspring shows a phenotype for green eyes, what is most likely the best explanation for this?
Black fur (A) is dominant to brown fur (a) and brown eyes (B) are dominant to blue eyes (b) in mice. Two mice are heterozygous for both traits. If one of the offspring shows a phenotype for green eyes, what is most likely the best explanation for this?
The best choice is that the individual has a mutation that accounts for his/her green eyes. This mutation would yield a new phenotype that was not a result of direct inheritance from the parent generation.
Codominance cannot only occur in one individual offspring; rather it would occur in some form in all offspring with respect to the given trait. Independent assortment always occurs in cases of typical Mendelian genetics.
The best choice is that the individual has a mutation that accounts for his/her green eyes. This mutation would yield a new phenotype that was not a result of direct inheritance from the parent generation.
Codominance cannot only occur in one individual offspring; rather it would occur in some form in all offspring with respect to the given trait. Independent assortment always occurs in cases of typical Mendelian genetics.
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In a population of fruit flies the allele for large wings is dominant over the allele for small wings. Two heterozygous parents are crossed and produce sixteen offspring. How many of these offspring will have large wings?
In a population of fruit flies the allele for large wings is dominant over the allele for small wings. Two heterozygous parents are crossed and produce sixteen offspring. How many of these offspring will have large wings?
Biologists use a diagram called a Punnett square to aid them in predicting traits that will be inherited by offspring. In this case both parents are heterozygous, meaning that they both carry one dominant allele (W) and one recessive allele (w). The Punnett square for this cross would look like this:
Because the W allele is dominant, squares with a W will produce the large wing trait. Three of the four possible genotypes from this cross carry the dominant allele, meaning that 75% of the offspring will have large wings. If the parents produce sixteen offspring, then twelve of them will show the large wing phenotype.
Biologists use a diagram called a Punnett square to aid them in predicting traits that will be inherited by offspring. In this case both parents are heterozygous, meaning that they both carry one dominant allele (W) and one recessive allele (w). The Punnett square for this cross would look like this:
Because the W allele is dominant, squares with a W will produce the large wing trait. Three of the four possible genotypes from this cross carry the dominant allele, meaning that 75% of the offspring will have large wings. If the parents produce sixteen offspring, then twelve of them will show the large wing phenotype.
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A particular flowering plant species exhibits dwarfism upon mutagenesis. Upon further observation, the mutation is exhibited by heterozygotes. The control lacks dwarfism and has a homozygous genotype. What kind of inheritance pattern does this mutation exhibit?
A particular flowering plant species exhibits dwarfism upon mutagenesis. Upon further observation, the mutation is exhibited by heterozygotes. The control lacks dwarfism and has a homozygous genotype. What kind of inheritance pattern does this mutation exhibit?
The trait that is expressed in heterozygotes is the dominant allele. Thus, the normal plant must be homozygous recessive. If dwarfism was a recessive trait, it would not be expressed in the heterozygotes.
The trait that is expressed in heterozygotes is the dominant allele. Thus, the normal plant must be homozygous recessive. If dwarfism was a recessive trait, it would not be expressed in the heterozygotes.
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In a fictional rabbit there is a gene allele that controls whether its tongue is keratinized—K—or not—k. A rabbit with the genotype of either KK or Kk has a keratinized tongue. A rabbit with the genotype of kk has a non-keratinized tongue. If a heterozygous male and female rabbit mate, then what is the probability that their offspring will be heterozygous for the gene that controls for tongue keratinization?
In a fictional rabbit there is a gene allele that controls whether its tongue is keratinized—K—or not—k. A rabbit with the genotype of either KK or Kk has a keratinized tongue. A rabbit with the genotype of kk has a non-keratinized tongue. If a heterozygous male and female rabbit mate, then what is the probability that their offspring will be heterozygous for the gene that controls for tongue keratinization?
Both of the parent's genotypes are Kk. This means that the offspring can be either KK, Kk, or kk.
Parental genotype:
Offspring probability:
Both of the parent's genotypes are Kk. This means that the offspring can be either KK, Kk, or kk.
Parental genotype:
Offspring probability:
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Which of the following describes a phenotype?
Which of the following describes a phenotype?
A genotype is the genetic makeup on an organism, while a phenotype is the composite of an organism’s observable traits. In short, the genotype determines the phenotype. The phenotype can also include any other observable traits, such as morphology, development, biochemical or physiological properties, phenology, behavior, and products of behavior. Environmental factors can also affect the phenotype of an organism (in addition to the inherited genotype).
A genotype is the genetic makeup on an organism, while a phenotype is the composite of an organism’s observable traits. In short, the genotype determines the phenotype. The phenotype can also include any other observable traits, such as morphology, development, biochemical or physiological properties, phenology, behavior, and products of behavior. Environmental factors can also affect the phenotype of an organism (in addition to the inherited genotype).
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Consider a rare plant that exhibits the phenotype of dark blue leaves (BB) as its dominant trait and and light blue leaves (bb) as its recessive trait. It flowers a bright yellow flower (YY) when dominant, and an orange flower (yy) when recessive.
When two dihybrid plants of the same species are crossed, what will be the expected phenotypic ratio of offspring that exhibit light blue leaves and yellow flowers?
Consider a rare plant that exhibits the phenotype of dark blue leaves (BB) as its dominant trait and and light blue leaves (bb) as its recessive trait. It flowers a bright yellow flower (YY) when dominant, and an orange flower (yy) when recessive.
When two dihybrid plants of the same species are crossed, what will be the expected phenotypic ratio of offspring that exhibit light blue leaves and yellow flowers?
Once you properly set up your punnet square of a dihybrid cross, you should obtain a phenotypic ratio of 9:3:3:1. There will be 9 plants with dark blue leaves/yellow flowers, 3 plants with light blue leaves/yellow flowers, 3 plants with dark blue leaves/orange flowers, and 1 plant with light blue leaves/orange flowers.
Once you properly set up your punnet square of a dihybrid cross, you should obtain a phenotypic ratio of 9:3:3:1. There will be 9 plants with dark blue leaves/yellow flowers, 3 plants with light blue leaves/yellow flowers, 3 plants with dark blue leaves/orange flowers, and 1 plant with light blue leaves/orange flowers.
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For a monohybrid cross of a gene that exhibits complete dominance, what will be the expected ratios for the phenotype and genotype?
For a monohybrid cross of a gene that exhibits complete dominance, what will be the expected ratios for the phenotype and genotype?
For better visualization of this explanation we can use eye color as an example. BB and BB will be brown eyes and bb will be blue eyes.
In a monohybrid cross you are dealing with only one gene. We can use "Bb" as an example for the gene as it is a hybrid of two alleles. BB & Bb are dominant and bb is recessive.
Setting up a punnet square of Bb x Bb we will get 4 results: BB, Bb, Bb, and bb.
The phenotype is what we see: eye color. Phenotype will be expressed the same for BB and Bb, therefore we have 3 that will express the dominant phenotype and 1 that will express the recessive phenotype; 3:1.
The genotype is the actual gene that creates the phenotype. So for this we have 3 different genes that arise from the monohybrid cross: BB, Bb, and bb. We get 1 homozygous dominant, 2 heterozygous, and 1 homozygous recessive; 1:2:1.
For better visualization of this explanation we can use eye color as an example. BB and BB will be brown eyes and bb will be blue eyes.
In a monohybrid cross you are dealing with only one gene. We can use "Bb" as an example for the gene as it is a hybrid of two alleles. BB & Bb are dominant and bb is recessive.
Setting up a punnet square of Bb x Bb we will get 4 results: BB, Bb, Bb, and bb.
The phenotype is what we see: eye color. Phenotype will be expressed the same for BB and Bb, therefore we have 3 that will express the dominant phenotype and 1 that will express the recessive phenotype; 3:1.
The genotype is the actual gene that creates the phenotype. So for this we have 3 different genes that arise from the monohybrid cross: BB, Bb, and bb. We get 1 homozygous dominant, 2 heterozygous, and 1 homozygous recessive; 1:2:1.
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Sharon has blonde hair. Her husband is heterozygous for brown hair, with brown being the dominant autosomal trait. What percent chance will their daughter have blonde hair?
Sharon has blonde hair. Her husband is heterozygous for brown hair, with brown being the dominant autosomal trait. What percent chance will their daughter have blonde hair?
The genotype for Sharon is rr, because blonde is a recessive trait therefore in order to have blonde hair she must be homozygous recessive. Her husband is Rr, because it states that he has brown hair, which is dominant, in addition to being heterozygous. When drawing out a punnet square, you will find the offspring will be Rr, Rr, rr and rr. Therefore, their daughter has 50% chance of having brown hair and 50% chance of having blonde hair.
The genotype for Sharon is rr, because blonde is a recessive trait therefore in order to have blonde hair she must be homozygous recessive. Her husband is Rr, because it states that he has brown hair, which is dominant, in addition to being heterozygous. When drawing out a punnet square, you will find the offspring will be Rr, Rr, rr and rr. Therefore, their daughter has 50% chance of having brown hair and 50% chance of having blonde hair.
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Sickle cell disease can be terrible and painful; however, the sickle cell trait (heterozygous for the sickle cell gene) is protective against malaria.
Molly is married to Fred. Molly has the recessive disorder of sickle cell anemia. Fred does not have the disease and is also not a carrier. What is the chance that Molly and Fred's children are all carriers of the disease?
Sickle cell disease can be terrible and painful; however, the sickle cell trait (heterozygous for the sickle cell gene) is protective against malaria.
Molly is married to Fred. Molly has the recessive disorder of sickle cell anemia. Fred does not have the disease and is also not a carrier. What is the chance that Molly and Fred's children are all carriers of the disease?
Since Molly is autosomal recessive (ss) and Fred is autosomal dominant (SS), all their children will be heterozygotes, or carriers and they will thus all be protected against malaria.
Since Molly is autosomal recessive (ss) and Fred is autosomal dominant (SS), all their children will be heterozygotes, or carriers and they will thus all be protected against malaria.
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