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Questions and Answers
In a scenario where a plant species exhibits incomplete dominance for flower color, with the alleles being red (R) and white (W), what phenotype would you expect in the F1 generation resulting from a cross between a homozygous red-flowered plant and a homozygous white-flowered plant?
In a scenario where a plant species exhibits incomplete dominance for flower color, with the alleles being red (R) and white (W), what phenotype would you expect in the F1 generation resulting from a cross between a homozygous red-flowered plant and a homozygous white-flowered plant?
- Pink flowers. (correct)
- Red flowers.
- Red flowers with some white spots.
- A blend of red and white flowers on the same plant.
Consider a dihybrid cross involving two traits: seed color (yellow or green) and seed shape (round or wrinkled). If you cross two plants that are heterozygous for both traits (YyRr x YyRr), what proportion of the offspring would you expect to have yellow seeds and wrinkled shape, assuming these genes assort independently?
Consider a dihybrid cross involving two traits: seed color (yellow or green) and seed shape (round or wrinkled). If you cross two plants that are heterozygous for both traits (YyRr x YyRr), what proportion of the offspring would you expect to have yellow seeds and wrinkled shape, assuming these genes assort independently?
- 9/16
- 1/16
- 3/16 (correct)
- 3/4
In a test cross, an individual with a dominant phenotype but unknown genotype is crossed with a homozygous recessive individual. If the offspring show a 1:1 ratio of dominant to recessive phenotypes, what does this indicate about the genotype of the unknown parent?
In a test cross, an individual with a dominant phenotype but unknown genotype is crossed with a homozygous recessive individual. If the offspring show a 1:1 ratio of dominant to recessive phenotypes, what does this indicate about the genotype of the unknown parent?
- The parent with the dominant phenotype is homozygous dominant.
- The parent with the dominant phenotype is heterozygous. (correct)
- The parent with the dominant phenotype is homozygous recessive.
- The parent with the dominant phenotype has a mutation.
A plant breeder is working with a species that exhibits co-dominance for petal color. One allele codes for red petals (R) and another for white petals (W). If a heterozygous plant (RW) is crossed with another heterozygous plant (RW), what is the probability of producing offspring with both red and white petals expressed?
A plant breeder is working with a species that exhibits co-dominance for petal color. One allele codes for red petals (R) and another for white petals (W). If a heterozygous plant (RW) is crossed with another heterozygous plant (RW), what is the probability of producing offspring with both red and white petals expressed?
A human trait shows a distinct difference in expression between males and females. Males are more likely to express the trait, and it is never passed from father to son. What type of inheritance is most likely responsible for this pattern?
A human trait shows a distinct difference in expression between males and females. Males are more likely to express the trait, and it is never passed from father to son. What type of inheritance is most likely responsible for this pattern?
What key step did Gregor Mendel undertake to ensure cross-pollination between pea plants with different traits?
What key step did Gregor Mendel undertake to ensure cross-pollination between pea plants with different traits?
If non-disjunction occurs during meiosis I in humans resulting in a sperm cell with two copies of chromosome 21, what condition will result if this sperm fertilizes a normal egg?
If non-disjunction occurs during meiosis I in humans resulting in a sperm cell with two copies of chromosome 21, what condition will result if this sperm fertilizes a normal egg?
A scientist observes that a certain variety of plant consistently produces offspring with a unique combination of traits not seen in the parental generation. Which of Mendel's laws is best exemplified by this observation?
A scientist observes that a certain variety of plant consistently produces offspring with a unique combination of traits not seen in the parental generation. Which of Mendel's laws is best exemplified by this observation?
Consider a family pedigree where a particular trait appears in every generation, and both males and females are equally affected. What is the most likely mode of inheritance for this trait?
Consider a family pedigree where a particular trait appears in every generation, and both males and females are equally affected. What is the most likely mode of inheritance for this trait?
In humans, ABO blood type is determined by three alleles: A, B, and O. A person with type AB blood marries a person with type O blood. What are the possible blood types of their offspring?
In humans, ABO blood type is determined by three alleles: A, B, and O. A person with type AB blood marries a person with type O blood. What are the possible blood types of their offspring?
In a species of bird, tail feather length is determined by a single gene with two alleles: L (long) and S (short). However, the environment plays a significant role; birds raised in nutrient-poor conditions always have shorter tails, regardless of their genotype. How would you best describe the determination of tail feather length in this bird species?
In a species of bird, tail feather length is determined by a single gene with two alleles: L (long) and S (short). However, the environment plays a significant role; birds raised in nutrient-poor conditions always have shorter tails, regardless of their genotype. How would you best describe the determination of tail feather length in this bird species?
In a certain species of beetles, wing color is determined by a single gene with two alleles: C^B for brown wings and C^Y for yellow wings. Heterozygous beetles (C^BC^Y) have mottled wings with both brown and yellow spots. If two mottled-winged beetles mate, what percentage of their offspring are expected to have brown wings?
In a certain species of beetles, wing color is determined by a single gene with two alleles: C^B for brown wings and C^Y for yellow wings. Heterozygous beetles (C^BC^Y) have mottled wings with both brown and yellow spots. If two mottled-winged beetles mate, what percentage of their offspring are expected to have brown wings?
What is the biological role of the stigma in a flowering plant?
What is the biological role of the stigma in a flowering plant?
A researcher is studying a newly discovered genetic disorder in humans. They analyze karyotypes from affected individuals and find that one chromosome pair has an abnormal number of chromosomes. Which genetic concept does this observation directly relate to?
A researcher is studying a newly discovered genetic disorder in humans. They analyze karyotypes from affected individuals and find that one chromosome pair has an abnormal number of chromosomes. Which genetic concept does this observation directly relate to?
In a population of butterflies, wing color is controlled by a single gene with three possible alleles: $A_1$, $A_2$, and $A_3$. How many different genotypes are possible in this population?
In a population of butterflies, wing color is controlled by a single gene with three possible alleles: $A_1$, $A_2$, and $A_3$. How many different genotypes are possible in this population?
What is the fundamental difference between a monohybrid cross and a dihybrid cross in genetics?
What is the fundamental difference between a monohybrid cross and a dihybrid cross in genetics?
Which of the following components of a flower is responsible for producing the male gametes?
Which of the following components of a flower is responsible for producing the male gametes?
A couple, both with no family history of hemophilia, has a son with hemophilia. What is the probability that their next child will also have hemophilia, assuming hemophilia is an X-linked recessive disorder?
A couple, both with no family history of hemophilia, has a son with hemophilia. What is the probability that their next child will also have hemophilia, assuming hemophilia is an X-linked recessive disorder?
Using a pedigree, you observe that a certain genetic condition appears to skip generations. What mode of inheritance is most likely?
Using a pedigree, you observe that a certain genetic condition appears to skip generations. What mode of inheritance is most likely?
Flashcards
Allele
Allele
An alternative form of a gene at a specific chromosome location.
Chromosome
Chromosome
A structure of DNA and proteins, carrying genetic information.
Fertilization
Fertilization
Fusion of sperm and egg to form a zygote.
F1 Generation
F1 Generation
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Heterozygous
Heterozygous
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Homozygous
Homozygous
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Hemizygous
Hemizygous
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Incomplete Dominance
Incomplete Dominance
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Phenotype
Phenotype
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Punnett Square
Punnett Square
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Trait
Trait
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Co-dominance
Co-dominance
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Monohybrid Cross
Monohybrid Cross
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Dihybrid Cross
Dihybrid Cross
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Gamete
Gamete
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Genetics
Genetics
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Multiple Alleles
Multiple Alleles
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Probability
Probability
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Segregation
Segregation
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Genome
Genome
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Study Notes
- Study notes for Chapters 11 & 14
Key Genetics Terms
- Allele: An alternative form of a gene at a specific location on a chromosome.
- Chromosome: A threadlike structure of DNA and proteins in the cell nucleus; humans have 23 pairs.
- Fertilization: The union of sperm and egg to form a zygote.
- F1 Generation: The first generation of offspring from a cross between parents.
- Heterozygous: Having two different alleles for a gene (e.g., Aa).
- Homozygous: Having two identical alleles for a gene (e.g., AA or aa).
- Hemizygous: Having only one copy of a gene, as with males for X-linked traits.
- Incomplete Dominance: A type of inheritance where neither allele is fully dominant, resulting in a blended phenotype.
- Phenotype: An organism's observable traits.
- Punnett Square: A tool for predicting genotypes and phenotypes of offspring.
- Trait: A characteristic determined by genes.
- Co-dominance: Both alleles are equally expressed (e.g., AB blood type).
- Gamete: A reproductive cell (sperm or egg) with half the number of chromosomes.
- Genetics: The study of heredity and inherited variation.
- Hybrid: Offspring of two different species or genetically different parents.
- Multiple Alleles: More than two alleles exist for a gene (e.g., ABO blood group).
- Probability: The likelihood of an event occurring.
- Segregation: Separation of alleles during gamete formation.
- Genome: The complete set of genes in a cell or organism.
- Karyotype: The number and appearance of chromosomes in a cell.
- Sex Chromosome: Chromosomes determining sex (X and Y in humans).
- Allosome: Another term for sex chromosomes (X and Y).
- Autosome: Non-sex chromosomes.
- Pedigree: A diagram showing the inheritance of traits in a family.
- Sex-linked Gene: A gene located on a sex chromosome.
- Non-disjunction: Failure of chromosomes to separate properly during cell division.
- Heredity: The passing of traits from parents to offspring.
Gregor Mendel's Pea Plant Experiments
- Mendel studied seven traits: flower color, seed color, seed shape, pod shape, pod color, flower position, and plant height.
- Principle of Dominance: One allele may mask the expression of another.
- Principle of Segregation: Alleles separate during gamete formation.
- Principle of Independent Assortment: Genes for different traits are inherited independently.
Flower Anatomy
- Anther: Produces pollen (male gametes).
- Filament: Supports the anther.
- Stigma: Receives pollen.
- Style: Connects the stigma to the ovary.
- Ovary: Contains ovules (female gametes).
Mendel's Cross-Pollination Method
- Mendel removed anthers to prevent self-pollination and manually transferred pollen from another plant.
Trait Types
- Single Allele Trait: Controlled by one gene with two alleles.
- Polygenic Trait: Controlled by multiple genes.
Genetic Crosses
- Monohybrid Cross: Involves one pair of contrasting traits (e.g., Aa x Aa yields a 3:1 phenotypic ratio).
- Dihybrid Cross: Involves two traits (e.g., AaBb x AaBb yields a 9:3:3:1 phenotypic ratio).
Probability in Genetics
- Probability predicts the likelihood of traits, and Punnett squares show the combinations
Test Crosses
- A test cross determines the genotype of an individual with a dominant phenotype by crossing with a homozygous recessive individual.
Non-Mendelian Genetics
- Incomplete Dominance: Results in a blended phenotype.
- Co-dominance: Both alleles are fully expressed.
- Multiple Alleles: More than two alleles for a gene.
- Polygenic Traits: Traits determined by multiple genes.
Environmental Influence on Genes
- The environment impacts traits (e.g., sunlight affects plant height).
Sex-Linked Traits and Disorders
- Sex-linked Genes: Located on sex chromosomes, especially the X chromosome.
- Sex-linked Disorders: Include color blindness, hemophilia, and Duchenne muscular dystrophy.
Karyotypes
- A karyotype displays an organism's chromosomes arranged in pairs.
- Humans have 22 pairs of autosomes and one pair of sex chromosomes (XX or XY).
Pedigrees
- Pedigrees trace trait inheritance in families.
- Circles represent females, squares represent males. Shaded shapes indicate affected individuals, while unshaded shapes indicate unaffected individuals.
Genetic Disorders
- Recessive Disorders: Require two copies of the recessive allele.
- Dominant Disorders: Require only one copy of the dominant allele.
Blood Types
- ABO Blood Group: Determined by A, B, and O alleles.
- Rh Factor: Determines positive (+) or negative (-) blood type.
Sex Determination
- XX chromosomes determine a female.
- XY chromosomes determine a male.
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