Question

In pea plants, the allele for red flower color, F, is completely dominant to the allele for white flower color, f. Complete the Punnett square showing the genotypes possible among the offspring when two heterozygous individuals are crossed. Use the information from the Punnett square to answer the second question.

In this cross between two heterozygous pea plants, what are the chances that an offspring with red flowers will be produced?

a. 75%
b. 3%
c. 50%
d. 25%

Answer 1

When crossing two heterozygous pea plants for flower color, the Punnett square predicts that the chances of an offspring having red flowers are 75%. This is because in the square, three out of the four possible genotypes (FF, Ff, and Ff) result in red flowers, given the complete dominance of the red allele (F) over the white allele (f).

Step-by-step explanation:

To complete a Punnett square showing the genotypes possible among the offspring when two heterozygous pea plants with alleles for red flower color (F) and white flower color (f) are crossed, we place the alleles from one parent across the top and the alleles from the other parent down the left side. Each parent, being heterozygous, will have one dominant allele (F) and one recessive allele (f).

The Punnett square would look like this:

• 
  
• Top row: F f
• 
  
• Left column: F f

We then fill in the squares:

• 
  
• Top left: FF
• 
  
• Top right: Ff
• 
  
• Bottom left: Ff
• 
  
• Bottom right: ff

From the Punnett square, we can see that there are three ways for offspring to have red flowers (FF, Ff, and Ff) and one way for them to have white flowers (ff). As the red flower color is completely dominant over white, offspring with either FF or Ff genotypes will have red flowers. Therefore, the chances that an offspring will have red flowers are 75% (or 3 out of 4). The correct answer to the question is a. 75%.

Learn more about Punnett square