Question

Which of the two options mentioned below is the ACCURATE description of the application of Punnett Squares?

a. It tells us the ratio in which the genotypes/ phenotypes of offspring in a given cross will/must appear.
b. It tells us the probability with which a particular genotype or phenotype can be expected to appear in the offspring

Answer 1

The answer would be option b. Punnet squares do not allow us to see the ration between geno and phenotypes, it only shows us the probablility of traits offspring would have.

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Answer 2

The Punnett Square predicts the probabilities of genotypes and phenotypes in offspring, based on the parental alleles. It does not guarantee ratios but provides expected probabilities for genetic outcomes.

Step-by-step explanation:

The Punnett Square is a tool used in genetics to predict the outcomes of a particular cross. The correct description of a Punnett Square's application is that it tells us the probability with which a particular genotype or phenotype can be expected to appear in the offspring.

This is because each combination of alleles has an equal chance of occurring. When all possible combinations of the parents' alleles - which represent the genotypes of their gametes - are considered and placed into a grid, we can see the expected frequencies of different genotypes and phenotypes in the offspring.

For example, in the case of true-breeding pea plants, where one possesses yellow seeds (YY) and the other green seeds (yy), a Punnett Square would only show the offspring as Yy, resulting in yellow seeds.

However, in a situation where both parents are heterozygous (Yy), we would expect a 3:1 phenotypic ratio - three yellow to one green. Therefore, the Punnett Square does not tell us the ratio in which the offspring genotypes/phenotypes will must appear, but rather the probability of each possibility.