Question

Calculate: Punnett squares can be used to predict probable outcomes of genetic crosses. To calculate probability, divide the number of one kind of possible outcome by the total number of all possible outcomes. For example, if you toss a coin, the chance it will land on heads is equal to 1 ÷ 2. This probability can be expressed as ½, 0.5, or 50%.

How many total possible outcomes are there?
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Complete the table below to show the number of outcomes and the probabilities in both fractions and percentages.

I I
Number of Outcomes I Fraction I Percentage
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FR FR
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FW FW
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FR FW
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Answer 1

In a Punnett square with heterozygous parents (Pp x Pp), there are four possible genotypes: PP, Pp, pP, and pp, resulting in probabilities of 25% for PP (purple), 50% for Pp or pP (purple), and 25% for pp (white). Thus, 75% of the offspring are expected to be purple and 25% white.

Step-by-step explanation:

To determine the number of total possible outcomes using a Punnett square, we need to consider the number of alleles each parent can contribute. For example, if we use the scenario where both parents are heterozygous for flower color (Pp), where 'P' is the dominant purple color allele and 'p' is the recessive white color allele, each parent can contribute either a 'P' or a 'p' allele. When we cross these, we have four possible outcomes: PP, Pp, pP, and pp. This gives us a total of four possible genetic combinations. When looking at the phenotypes, the probability for offspring to be purple (PP or Pp) is 3 out of 4, and for white (pp) is 1 out of 4.

To fill in the table with the number of outcomes and their probabilities, we consider each possible genotype and its corresponding phenotype. Since 'P' is dominant, both PP and Pp result in purple flowers, while pp results in white flowers.

• Number of Outcomes for PP (FRFR): 1
• Fraction: 1/4
• Percentage: 25%

• Number of Outcomes for Pp or pP (FRFW): 2
• Fraction: 1/2
• Percentage: 50%

• Number of Outcomes for pp (FWFW): 1
• Fraction: 1/4
• Percentage: 25%

Therefore, we can predict that 75% of the offspring will be purple, and 25% of the offspring will be white.

Answer 2

I think it’s

FR FR: 3 outcomes; 1/4, 2/4, 1/4; 25%, 50%, 25%

FW FW: 3 outcomes; 1/4, 2/4, 1/4; 25%, 50%, 25%

FR FW: 4 outcomes; 1/4, 1/4, 1/4, 1/4; 25%, 25%, 25%, 25%