Genetics: Punnett Square

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 bb.

Front

What does heterozygous mean?

Back

Heterozygous refers to having two different alleles for a particular gene, such as 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 a genotype?

Back

Genotype is the genetic constitution of an individual, represented by the alleles it possesses.

Front

What is the difference between dominant and recessive alleles?

Back

Dominant alleles are expressed in the phenotype even when only one copy is present, while recessive alleles are only expressed when two copies are present.

Front

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

Back

50% tall; 50% short.

Front

What is the expected phenotype ratio when two heterozygous red flowers are crossed?

Back

75% red; 25% white.

Front

What is the expected phenotype ratio when two heterozygous white rabbits are crossed?

Back

75% white; 25% brown.

Front

What is the genotype of the offspring when two white flowers (rr) are crossed?

Back

100% homozygous recessive (rr).