Genetics: 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.

Front

What does 'homozygous' mean?

Back

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

Front

What does 'heterozygous' mean?

Back

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

Front

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., B in Bb).

Front

What is a recessive allele?

Back

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

Front

What is the probability of getting a homozygous dominant offspring from a cross of BB x Bb?

Back

The probability is 50%.

Front

What is the probability of getting a homozygous recessive offspring from a cross of Rr x Rr?

Back

The probability is 25%.

Front

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

Back

You fill in the Punnett Square with the alleles from each parent and then count the combinations to find the probabilities.

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What does 'genotype' refer to?

Back

Genotype refers to the genetic makeup of an organism, represented by the alleles (e.g., BB, Bb, or rr).

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What does 'phenotype' refer to?

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Phenotype refers to the observable traits of an organism, which result from the genotype and environmental influences.