Punnett Squares

Front

What is a Punnett Square?

Back

A Punnett Square is a diagram used to predict the outcome of a genetic cross by showing the possible combinations of alleles from the parents.

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What does homozygous mean?

Back

Homozygous refers to having two identical alleles for a particular gene, either dominant (AA) or recessive (aa).

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What does heterozygous mean?

Back

Heterozygous refers to having two different alleles for a particular gene (Aa).

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What is the phenotype?

Back

The phenotype is the observable physical or biochemical characteristics of an organism, determined by its genotype.

Front

What is the genotype?

Back

The genotype is the genetic constitution of an individual, represented by the alleles (e.g., AA, Aa, aa).

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What is a dominant allele?

Back

A dominant allele is an allele that expresses its trait even when only one copy is present (e.g., A in Aa).

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What is a recessive allele?

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A recessive allele is an allele that only expresses its trait when two copies are present (e.g., aa).

Front

How do you determine the probability of offspring traits using a Punnett Square?

Back

By filling in the Punnett Square with the alleles from each parent and counting the combinations to find the ratio of possible genotypes and phenotypes.

Front

If a homozygous dominant plant (PP) is crossed with a homozygous recessive plant (pp), what will the offspring's phenotype be?

Back

All offspring will have the phenotype of the dominant trait (Purple).

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What is the probability of getting a recessive trait from two heterozygous parents?

Back

There is a 25% probability of getting a recessive trait from two heterozygous parents (Aa x Aa).