Questions and Answers
Alleles are described as ______.
A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds. The seeds of all of the offspring are yellow. Why?
According to Mendel's law of segregation, ______.
In humans, the presence or absence of dimples is a trait controlled by a single gene. What is the genotype of an individual who is heterozygous for dimples?
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To determine the phenotype of an individual who expresses a dominant trait, you would cross that individual with an individual who ______.
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A couple has two female children. What is the probability that their next child will be male?
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In humans, free earlobes (E) are dominant to attached earlobes (e) and the presence of freckles (F) is dominant to the absence of freckles (f). If an individual heterozygous for both of these traits were to mate with an individual with attached earlobes and no freckles, what is the probability of having a child with attached earlobes and freckles?
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The ______ is most commonly found in nature.
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Achondroplasia is a form of dwarfism caused by a dominant allele. The homozygous dominant genotype causes death, so individuals who have this condition are all heterozygotes. If a person with achondroplasia mates with a person who does not have achondroplasia, what percentage of their children would be expected to have achondroplasia?
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An individual with the blood group genotype LMLN has the phenotype MN. What is the relationship between the LM and LN alleles?
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Many human traits, such as our performance on intelligence tests or our susceptibility to heart disease, are ______.
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What is the best definition of a purebred plant?
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What would result from a mating between a purebred purple-flowered pea plant and a purebred white-flowered pea plant?
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Alleles are described as ______.
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A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds. The seeds of all of the offspring are yellow. Why?
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A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds. The F1 plants have yellow seeds. What is the expected phenotypic ratio of seed color of the offspring of an F1 × F1 cross?
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According to Mendel's law of segregation, ______.
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Attached earlobes are recessive to free earlobes. What genotypic ratio is expected when an individual with attached earlobes mates with an individual heterozygous for free earlobes?
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Study Notes
Genetic Basics
- Alleles are alternate versions of a gene that determine traits.
- Dominance relationships exist; for example, the yellow seed allele is dominant over the green seed allele.
Mendel's Laws
- Mendel's law of segregation states that gametes carry one copy of each allele, allowing for genetic variation.
- Phenotypic ratios in offspring can predict outcomes; a cross of F1 plants (yellow seeds) produces a 3:1 ratio of seed color in future generations.
Genotype and Phenotype Dynamics
- Heterozygous individuals have one dominant and one recessive allele (e.g., Dd for dimples).
- To determine if an individual expressing a dominant trait is homozygous or heterozygous, they should be crossed with a homozygous recessive individual.
Probability and Genetic Predictions
- The probability of having male offspring remains 50%, independent of the genders of previous children.
- When crossing a heterozygous individual for two traits with a homozygous recessive, there’s a 25% chance for traits (e.g., attached earlobes and freckles).
Traits and Genetic Conditions
- Free earlobes (E) dominate over attached earlobes (e) and freckles (F) dominate over no freckles (f).
- Certain conditions, such as achondroplasia (a dominant trait), have specific inheritance patterns resulting in a potential 50% chance of expression in offspring when one parent carries the trait.
Nature and Diversity of Traits
- Wild-type traits are the most commonly observed phenotypes in nature, often serving as reference points in genetic studies.
- Many human traits, including intelligence and disease susceptibility, are influenced by both genes and environmental factors, showcasing the complexity of genetic expression.
Purebred and Hybrid Concepts
- A purebred plant self-fertilizes to produce offspring identical to the parent.
- Crossing purebred plants of contrasting phenotypes (like flower color) results in hybrids, demonstrating the introduction of diverse genetic material.
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Test your knowledge of genetic concepts in BISC 002 Chapter 9 with these flashcards. Explore key terms like alleles and inheritance patterns through interactive questions and answers. Perfect for revision or reinforcing your understanding of genetics.
