Questions and Answers
What is the best definition of a purebred plant?
self-fertilizes to produce offspring identical to the parent
A mating between a purebred purple-flowered pea plant and a purebred white-flowered pea plant would produce?
hybrid
Alleles are described as?
alternate versions of a gene
Why do all offspring of a purebred plant that produces yellow seeds x purebred plant that produces green seeds have yellow seeds?
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What is the expected phenotypic ratio of seed color of the offspring of an F1 × F1 cross when yellow seeds are dominant?
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According to Mendel's law of segregation, ________.
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What genotypic ratio is expected when an individual with attached earlobes mates with an individual heterozygous for free earlobes?
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What are the offspring produced from Mendel's cross of purebred purple-flowered with purebred white-flowered plants?
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What is the probability of having a child with attached earlobes when an individual with attached earlobes mates with an individual heterozygous for free earlobes?
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What is the genotype of an individual who is heterozygous for dimples?
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An individual who is homozygous carries?
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Which of these crosses will produce only heterozygous offspring?
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What name is given to the specific location of a gene on a chromosome?
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What is the expected phenotypic ratio of a cross between an RrYy and an rryy individual?
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What does it mean if an individual with genotype AaBb produces four different gametes in equal proportions?
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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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What is the probability of having a child with attached earlobes and freckles when mating with an individual heterozygous for both traits?
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What data or test would you seek to determine whether or not a trait is sex-linked?
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The ________ is most commonly found in nature.
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An individual heterozygous for cystic fibrosis is?
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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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Which technique is used to collect fetal cells during pregnancy for genetic testing?
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What is the key to the recognition of incomplete dominance?
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What is the relationship between the alleles for hair texture in curly and straight hair when their offspring are wavy?
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What is the probability that the child of an individual with wavy hair and an individual with straight hair will have curly hair?
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What is the key to the recognition of codominance?
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What is the relationship between the LM and LN alleles in an individual with blood group genotype LMLN?
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What type of inheritance is the phenotype of Marfan syndrome an example of?
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What is key to recognition of a trait whose expression is determined by the effects of two or more genes (polygenic inheritance)?
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In humans, what trait is best explained as being polygenic?
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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 basis of Mendel's laws?
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________ genes violate Mendel's principle of independent assortment.
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What is the best explanation for a BbCc × bbcc cross producing offspring in a 5:5:1:1 phenotypic ratio?
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A dihybrid cross produces 30 recombinant offspring out of a total of 1,000 offspring. What is the recombination frequency of the two gene pairs?
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The recombination frequency between gene B and gene C is 11%. The recombination frequency between gene B and gene D is 5%. The recombination frequency between gene C and gene D is 15%. What would be the arrangement of these genes on a linkage map?
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Linked genes are usually?
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Assume that having three nostrils is inherited as a sex-linked trait on the Y chromosome. What is the probability that the three-nostriled man's grandson has three nostrils?
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Can a man with normal color vision father a daughter who is red-green color-blind?
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What is the expected outcome of a cross between a homozygous recessive woman and a man with hypophosphatemia?
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Experience with dog breeding has taught geneticists?
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Study Notes
Genetics and Plant Breeding
- A purebred plant self-fertilizes to produce offspring identical to itself.
- Crossing purebred purple-flowered pea plants and purebred white-flowered pea plants results in hybrids.
Alleles and Dominance
- Alleles are alternate versions of a gene; dominant alleles mask the effect of recessive alleles.
- A yellow seed allele is dominant over a green seed allele, leading to all offspring of a cross displaying yellow seeds.
Mendelian Ratios and Laws
- F1 generation from a yellow and green seed cross displays a phenotypic ratio of 3:1 in subsequent offspring.
- Mendel's law of segregation states each gamete carries one allele for each gene.
Genotypic Ratios and Genetic Crosses
- Mating an attached earlobe individual with a heterozygous free earlobe individual results in a genotypic ratio of 1:1.
- For a purebred purple-flowered cross, all offspring will be heterozygotes with the purple allele being dominant.
Phenotypic Probabilities
- Probability of having a child with attached earlobes from a homozygous attached earlobe parent and a heterozygous parent is 50%.
- For an individual heterozygous for freckles mating with someone with attached earlobes and no freckles, the probability of a child with both traits is 25%.
Genetic Testing and Traits
- Collection of fetal cells for genetic testing can be performed via amniocentesis.
- Recognition of incomplete dominance reveals that the heterozygote displays a phenotype intermediate to the homozygotes.
Important Genetic Concepts
- Codominance occurs when the heterozygote displays both homozygote phenotypes.
- Marfan syndrome exemplifies pleiotropy, where a single allele affects multiple traits (height, cardiovascular issues, eye defects).
Polygenic Inheritance
- Traits like human height are influenced by multiple genes, showing variation along a continuum.
- Traits influenced by both genetics and environment affect characteristics such as intelligence and disease susceptibility.
Mendel's Laws and Gene Linkage
- Mendel's laws are based on chromosomal behavior during meiosis.
- Linked genes are typically located close together on a chromosome and can affect phenotypic ratios in offspring.
Gene Mapping and Recombination Frequencies
- A dihybrid cross producing 30 recombinant offspring out of 1,000 indicates a 3% recombination frequency.
- On a linkage map, the arrangement of genes might be determined by their recombination frequencies (e.g., DBC).
Sex-Linked Traits
- Sex-linked traits, such as red-green color blindness, show distinct inheritance patterns based on the sex chromosomes.
- Inherited sex-linked dominant traits yield all daughters and no sons exhibiting the trait when crossed with a homozygous recessive individual.
Dog Breeding Insights
- Geneticists observe that geographically isolated dog breeds may be selected for different traits, resulting in diverse dog breeds.
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Description
Test your knowledge on the principles of genetics, including Mendelian ratios, alleles, and dominances in plant breeding. This quiz covers topics such as purebred plants, genetic crosses, and the laws of inheritance as proposed by Gregor Mendel.
