Understanding Monohybrid and Dihybrid Crosses in Mendelian Genetics
What is the difference between a monohybrid cross and a dihybrid cross in the context of Mendelian genetics?
a. In a monohybrid cross, two different traits are considered, while a dihybrid cross involves the examination of a single trait.
b. A monohybrid cross investigates the inheritance of a single trait, while a dihybrid cross studies the inheritance of two different traits simultaneously.
c. Monohybrid and dihybrid crosses are terms used interchangeably and have no distinct differences.
d. Both monohybrid and dihybrid crosses examine the inheritance of multiple traits.
Final answer:
The correct answer is that a monohybrid cross involves one trait, while a dihybrid cross involves two traits. Monohybrid crosses use a 2x2 Punnett square, whereas dihybrid crosses use a 4x4 Punnett square to display all possible allele combinations.
Explanation:
The correct answer is b. A monohybrid cross investigates the inheritance of a single trait, while a dihybrid cross studies the inheritance of two different traits simultaneously.
Monohybrid Cross vs. Dihybrid Cross
In Mendelian genetics, a monohybrid cross focuses on the inheritance of one characteristic or trait. When considering a monohybrid cross, such as the color of pea plants (yellow or green), the Punnett square will have four squares, each combination representing the alleles inherited from the parents. If we have parents with genotypes YY (yellow) and yy (green), all offspring from such a cross are Yy (yellow).
A dihybrid cross, on the other hand, considers two traits at once - for instance, seed color (yellow or green) and seed shape (round or wrinkled). The Punnett square for a dihybrid cross has sixteen squares, representing all possible combinations of alleles from each parent. For a plant of genotype AaBb self-pollinating, the gamete genotypes could be AB, Ab, aB, or ab. Mendel’s experiments with dihybrid crosses led him to establish the law of independent assortment.