DRAW IT Two pea plants heterozygous for the characters of pod color and pod shape are crossed. Draw a Punnett square to determine the phenotypic ratios of the offspring.

Verified step by step guidance

1. Step 1: Identify the genotypes of the parent plants. Since they are heterozygous for both traits, their genotypes are RrGg, where 'R' represents the dominant allele for round shape, 'r' for wrinkled shape, 'G' for green color, and 'g' for yellow color.
2. Step 2: Determine the possible gametes each parent can produce. For a heterozygous plant, the possible gametes are RG, Rg, rG, rg.
3. Step 3: Draw a 4x4 Punnett square. Label the top with the possible gametes of one parent and the side with the possible gametes of the other parent.
4. Step 4: Fill in the Punnett square. Each box represents a possible genotype of the offspring. Combine the alleles from the top and the side to fill in each box.
5. Step 5: Determine the phenotypic ratios. Count the number of each phenotype (round green, round yellow, wrinkled green, wrinkled yellow) and express it as a ratio.

Key Concepts

Punnett Square

A Punnett square is a diagram used in genetics to predict the genotypes of offspring from a cross between two parents. It organizes the possible combinations of alleles from each parent, allowing for a visual representation of genetic variation. By filling in the square with the alleles, one can easily determine the potential genotypes and phenotypes of the offspring.

Heterozygous

Heterozygous refers to an organism that has two different alleles for a particular gene, one inherited from each parent. In the context of the pea plants, being heterozygous for pod color and shape means that each plant carries one dominant and one recessive allele for these traits. This genetic variation is crucial for understanding the potential outcomes of the cross.

Phenotypic Ratio

The phenotypic ratio is the ratio of different phenotypes (observable traits) that result from a genetic cross. It is derived from the genotypic ratios obtained from the Punnett square and indicates the likelihood of each phenotype appearing in the offspring. For example, in a dihybrid cross, the phenotypic ratio can reveal the expected distribution of traits such as pod color and shape.