Podcast
Questions and Answers
In a scenario where a plant has the genotype Aa, where 'A' is the dominant allele for tallness and 'a' is the recessive allele for shortness, what phenotype will the plant express?
In a scenario where a plant has the genotype Aa, where 'A' is the dominant allele for tallness and 'a' is the recessive allele for shortness, what phenotype will the plant express?
- A blend of tallness and shortness
- Neither tall nor short
- Short
- Tall (correct)
Consider a monohybrid cross between two pea plants, both heterozygous for flower color (Pp), where 'P' represents the dominant allele for purple flowers and 'p' represents the recessive allele for white flowers. What is the probability of producing offspring with white flowers?
Consider a monohybrid cross between two pea plants, both heterozygous for flower color (Pp), where 'P' represents the dominant allele for purple flowers and 'p' represents the recessive allele for white flowers. What is the probability of producing offspring with white flowers?
- 75%
- 25% (correct)
- 50%
- 0%
If two parents with genotypes Aa and aa are crossed, what percentage of their offspring would be expected to have the genotype aa?
If two parents with genotypes Aa and aa are crossed, what percentage of their offspring would be expected to have the genotype aa?
- 25%
- 0%
- 75%
- 50% (correct)
Which of the following statements accurately describes the relationship between genotype and phenotype?
Which of the following statements accurately describes the relationship between genotype and phenotype?
In genetics, what does it mean for an organism to be described as 'homozygous' for a particular trait?
In genetics, what does it mean for an organism to be described as 'homozygous' for a particular trait?
What is the primary purpose of using a Punnett square in genetic studies?
What is the primary purpose of using a Punnett square in genetic studies?
In a monohybrid cross, if both parents are heterozygous for a trait, what phenotypic ratio is expected in the offspring according to Mendel's Law of Dominance?
In a monohybrid cross, if both parents are heterozygous for a trait, what phenotypic ratio is expected in the offspring according to Mendel's Law of Dominance?
Consider a scenario where 'B' represents the dominant allele for black fur and 'b' represents the recessive allele for brown fur in rabbits. If a heterozygous black fur rabbit (Bb) is crossed with a brown fur rabbit (bb), what percentage of the offspring is expected to have black fur?
Consider a scenario where 'B' represents the dominant allele for black fur and 'b' represents the recessive allele for brown fur in rabbits. If a heterozygous black fur rabbit (Bb) is crossed with a brown fur rabbit (bb), what percentage of the offspring is expected to have black fur?
If a plant breeder wants to ensure that a plant with a dominant trait consistently produces offspring with the same dominant trait, what genotype should the parent plant have?
If a plant breeder wants to ensure that a plant with a dominant trait consistently produces offspring with the same dominant trait, what genotype should the parent plant have?
Which of the following crosses would result in offspring where all individuals display the dominant phenotype, assuming single-gene inheritance where 'A' is dominant and 'a' is recessive?
Which of the following crosses would result in offspring where all individuals display the dominant phenotype, assuming single-gene inheritance where 'A' is dominant and 'a' is recessive?
Flashcards
What is a gene?
What is a gene?
A section of DNA that determines a specific characteristic or trait.
What are alleles?
What are alleles?
Different forms of a gene that determine variations in a trait.
What is a dominant allele?
What is a dominant allele?
An allele that will be expressed if at least one copy is present.
What is a recessive allele?
What is a recessive allele?
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What is a genotype?
What is a genotype?
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What is a phenotype?
What is a phenotype?
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What does homozygous mean?
What does homozygous mean?
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What does heterozygous mean?
What does heterozygous mean?
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What is a Punnett Square?
What is a Punnett Square?
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What is a monohybrid cross?
What is a monohybrid cross?
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Study Notes
- A gene is a segment of DNA that determines a specific trait.
- Alleles are different forms of a gene.
Types of Alleles
- A dominant allele (e.g., "A") expresses its trait when at least one is present.
- A recessive allele (e.g., "a") expresses its trait only when two are present.
Genotypes vs. Phenotypes
- Genotype refers to the genetic makeup (e.g., AA, Aa, or aa).
- Phenotype refers to the physical expression of the trait.
Homozygous vs. Heterozygous
- Homozygous (purebred) have two identical alleles (AA or aa).
- Heterozygous (hybrid) have one dominant and one recessive allele (Aa).
Punnett Square
- A Punnett Square is a diagram to predict offspring genetic combinations from a cross between parents.
- To use a Punnett Square:
- Determine parental genotypes.
- Set up the square with one parent's alleles across the top and the other down the side.
- Fill in the squares by combining alleles.
- Analyze the results to determine genotype and phenotype ratios.
Example Punnett Square (Aa x aa)
- Genotypic ratio: 2 Aa : 2 aa
- Phenotypic ratio: 2 dominant : 2 recessive
Monohybrid Cross
- A monohybrid cross examines the inheritance of one trait between two individuals.
Example: Tall (T) vs. Short (t) Plants
- "T" is dominant for tall height.
- "t" is recessive for short height.
- Cross of two heterozygous (Tt) plants yields:
- Genotypic ratio: 1 TT : 2 Tt : 1 tt
- Phenotypic ratio: 3 Tall : 1 Short
- Happens according to Mendel’s Law of Dominance, where the dominant trait is expressed in heterozygous individuals.
Key Takeaways
- Genes determine traits; alleles are variations of genes.
- Dominant alleles mask recessive alleles.
- Punnett Squares predict offspring outcomes.
- Monohybrid crosses focus on one trait, often showing a 3:1 phenotype ratio from heterozygous parents.
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