Punnett Squares

Use the Punnett square to answer the question that follows.

In a monohybrid cross between two organisms heterozygous for a particular trait (Ff), what would be the predicted ratio of the offspring’s genotypes?

The Punnett square shows the cross between cabbage butterflies. B = white and b = yellow.

Why are all the offspring white?

A red flowered plant (RR) is crossed with a white flowered plant (WW) and produces plants with pink flowers (RW). If two pink flowered plants are crossed, what color offspring could be produced?

In a gerbil population, the gene for coarse hair (H) is dominant, while the gene for smooth hair (h) is recessive. One pet store found that most of their customers want coarse-haired gerbils. Which cross between male and female gerbils will produce the greatest number of coarse-haired offspring?

A snapdragon plant with red flowers (RR) is crossed with a snapdragon plant with white flowers (WW). Snapdragon flowers show incomplete dominance. A Punnett square of the cross is shown below.

If the cross produces four offspring, how many of each color flower would likely be produced?

Allele A is dominant in mice and allele a is recessive. Two mice with the gene combination Aa breed and produce four offspring as shown below.

Which offspring has the recessive phenotype?

Which best describes what a Punnett square determines?