Genetics: Punnett Square

Front

What is a Punnett Square?

Back

A Punnett Square is a diagram used to predict the genotype and phenotype combinations of offspring from a genetic cross.

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What does homozygous mean?

Back

Homozygous refers to having two identical alleles for a particular gene (e.g., BB or bb).

Front

What does heterozygous mean?

Back

Heterozygous refers to having two different alleles for a particular gene (e.g., Bb).

Front

What is a genotype?

Back

Genotype is the genetic makeup of an organism, represented by the alleles it possesses (e.g., BB, Bb, or bb).

Front

What is a phenotype?

Back

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

Front

What is the law of segregation?

Back

The law of segregation states that during the formation of gametes, the two alleles for a trait separate from each other.

Front

What is the probability of obtaining a homozygous recessive offspring from a cross between two heterozygous parents?

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25%.

Front

If a tall plant (Tt) is crossed with a short plant (tt), what are the possible phenotypes of the offspring?

Back

50% tall and 50% short.

Front

What is the expected phenotype ratio of offspring from a cross between two heterozygous red flowers?

Back

75% red and 25% white.

Front

What is the expected genotype ratio of offspring from a cross between two heterozygous red flowers?

Back

25% homozygous dominant, 50% heterozygous, 25% homozygous recessive.