Punnett Squares

Segments of DNA that code for a specific trait.

• Genes

• Phenotype

• Heterozygous

• Genotype

One half of a genotype, given by one of your parents.

• Phenotype

• Genes

• Alleles

• Recessive Trait

Two alleles that code for a specific trait.

• Phenotype

• Genotype

• Recessive trait

• Homozygous

The physical appearance of an organism. (This is the trait you can see.)

• Genotype

• Phenotype

• Gene

• Allele

A trait that masks or covers a recessive trait. It is represented by a capital letter. Example: AA or Aa

• Homozygous

• Genotype

• Recessive trait

• Dominant trait

A trait that is usually masked or covered by a dominant trait. When no dominant trait is present, the trait is shown. It is represented by two lowercase letters. Example: aa or bb

• Heterozygous

• Recessive trait

• Homozygous

• Dominant trait

A genotype with either two recessive alleles or two dominant alleles. Example: AA or aa

• Heterozygous

• Homozygous

• Recessive trait

• Phenotype

A genotype with two different alleles - one dominant and one recessive. Example: Aa

• Homozygous

• Dominant trait

• Heterozygous

• Phenotype

In a cross between two heterozygous pea plants, how many different genotypes are possible?

• 1

• 2

• 3

• 4

Is it possible for a brown-haired (BB) parent and a red-haired (bb) parent to have a red-haired child?

• yes

• no

• maybe