Use the Punnett Square below to answer the question.
YY or Yy = yellow flowers
yy = white flowers
GG or Gg = green seeds
gg = black seeds
What percent of offspring are homozygous recessive for both traits?
A. $25 \%$
B. $6.3 \%$
C. $18.7 \%
Answer (2)
Identify the number of offspring with the 'yygg' genotype from the Punnett square.
Calculate the fraction of 'yygg' offspring: 16 1 .
Convert the fraction to a percentage: 16 1 × 100 = 6.25% .
The percentage of offspring that are homozygous recessive for both traits is 6.25% .
Explanation
Analyze the problem and data We are given a Punnett square that shows the possible genotypes of offspring for two traits: flower color and seed color. We need to find the percentage of offspring that are homozygous recessive for both traits, which means they have the genotype 'yygg'.
Identify offspring with 'yygg' genotype First, let's examine the Punnett square to identify the offspring with the genotype 'yygg'. Looking at the Punnett square, we can see that there is 1 offspring with the 'yygg' genotype.
Calculate the percentage Now, we need to calculate the percentage of 'yygg' offspring out of the total number of offspring. The Punnett square represents 16 possible offspring genotypes in total. So, we will divide the number of 'yygg' offspring by the total number of offspring (16).
Convert to percentage The fraction of offspring with the 'yygg' genotype is 16 1 . To convert this fraction to a percentage, we multiply by 100:
Perform the calculation 16 1 × 100 = 6.25
State the final answer Therefore, 6.25% of the offspring are homozygous recessive for both traits.
Examples
Understanding the inheritance of traits is crucial in agriculture. For example, a farmer might want to know the probability of obtaining plants with specific desirable traits, such as disease resistance (dominant) and high yield (recessive). By using Punnett squares and probability calculations, the farmer can predict the outcome of crosses and make informed decisions about which plants to breed to maximize the chances of obtaining the desired combination of traits in their crops. This helps in optimizing resource allocation and improving crop productivity.
The percentage of offspring that are homozygous recessive for both traits (yygg) is calculated by identifying the genotype in a Punnett square. There is 1 instance of 'yygg' out of 16 total genotype possibilities, leading to a percentage of 6.25%. The correct answer choice is B. 6.3%.
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