In a monohybrid cross, what is a Punnett square primarily used for?

• A. To calculate the physical distance between two linked genes on a chromosome
• B. To predict the possible genotypes and phenotypes of offspring and their expected proportions from a given parental cross
• C. To determine the DNA nucleotide sequence of a gene responsible for a trait
• D. To identify which allele is dominant by directly measuring its expression level in heterozygotes

Answer: (B)

Verified step by step guidance

1. Understand that a monohybrid cross involves one gene with two different alleles, typically one dominant and one recessive.
2. Recognize that a Punnett square is a diagrammatic tool used to visualize all possible combinations of alleles from the parental gametes.
3. Set up the Punnett square by placing the alleles from one parent along the top and the alleles from the other parent along the side.
4. Fill in the squares by combining the alleles from the corresponding row and column to show all possible genotypes of the offspring.
5. Use the completed Punnett square to determine the expected proportions of genotypes and phenotypes among the offspring.