Genetics Test Cross

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What is a test cross in genetics?

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A test cross is a breeding experiment used to determine the genotype of an individual exhibiting a dominant trait by crossing it with a homozygous recessive individual.

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What does homozygous mean?

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Homozygous refers to having two identical alleles for a particular gene, such as WW or ww.

Front

What does heterozygous mean?

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Heterozygous refers to having two different alleles for a particular gene, such as Ww.

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What is the principle of dominance in genetics?

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The principle of dominance states that in a heterozygote, one allele may conceal the presence of another allele.

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What is the phenotypic ratio expected from a monohybrid cross?

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The expected phenotypic ratio from a monohybrid cross is typically 3:1 for dominant to recessive traits.

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What is the genotypic ratio expected from a monohybrid cross?

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The expected genotypic ratio from a monohybrid cross is 1:2:1 for homozygous dominant, heterozygous, and homozygous recessive genotypes.

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How can you determine if an organism with a dominant phenotype is homozygous or heterozygous?

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By performing a test cross with a homozygous recessive organism; if any offspring show the recessive phenotype, the organism is heterozygous.

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What is the significance of using a homozygous recessive organism in a test cross?

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Using a homozygous recessive organism ensures that any recessive traits will be expressed in the offspring, allowing for clear determination of the unknown genotype.

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What is the expected outcome of crossing two heterozygous organisms (Tt x Tt) for a trait?

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The expected outcome is 75% showing the dominant trait and 25% showing the recessive trait.

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What is the difference between genotype and phenotype?

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Genotype refers to the genetic makeup of an organism, while phenotype refers to the observable traits or characteristics.