Final answer:
A Punnett square is a tool used in genetics to predict the possible genotypes of offspring from two parents, applying probability to determine traits inheritance patterns, such as dominant or recessive. It can show the proportions of heterozygous or homozygous offspring and predict the phenotypes of offspring.
Step-by-step explanation:
What is a Punnett Square?
A Punnett square is a predictive tool used in genetics to determine the possible genotypes of offspring from a cross between two parents. It applies the rules of probability to predict how alleles from each parent can combine and what genotypes the offspring might have.
Information Provided by a Punnett Square
A Punnett square can provide several crucial pieces of information about genetic crosses: it can predict the likelihood of certain traits being passed on, the possible genotypes of the offspring, and from the genotypes, we can infer the phenotypes - physical expressions of the traits. If the pattern of inheritance such as dominant or recessive alleles is known, it can show expected phenotypic ratios. This can help determine if an organism will be heterozygous or homozygous for a certain allele and can predict the percentages of offspring that would display certain genetic disorders in humans, such as cystic fibrosis or Huntington's disease.
Examples of Using a Punnett Square
If we consider a cross between two plants where one allele (S) codes for long stems and is dominant to the other allele (s) for short stems, we could use a Punnett square to calculate that the offspring from an Ss x ss cross would result in 50% having long stems (Ss or SS) and 50% having short stems (ss), assuming S is the dominant allele.