What is the difference between a monohybrid cross and a dihybrid cross?
Understanding Monohybrid and Dihybrid Crosses
Monohybrid cross: In genetics, a monohybrid cross is a breeding experiment between two individuals that are heterozygous for a single trait. This means that they carry two different alleles for that specific trait. For example, if we consider the trait of flower color, one parent may have the genotype BB (dominant allele for purple flowers) and the other parent bb (recessive allele for white flowers). The resulting offspring from this type of cross would all be heterozygous (Bb) and display the dominant purple flower color.
Dihybrid cross: On the other hand, a dihybrid cross involves the study of two different traits that are inherited independently of each other. In this type of cross, both parents are heterozygous for two different traits. For instance, if we look at the traits of flower color and flower shape, one parent may have the genotype Aa (allele A for red flowers) and Bb (allele B for round shape) while the other parent has aa (allele a for white flowers) and BB (allele B for wrinkled shape). The offspring resulting from this type of cross would exhibit a combination of both traits and follow the principles of independent assortment.
Final answer:
A monohybrid cross deals with one trait and a single pair of alleles, resulting in a 3:1 phenotypic ratio, whereas a dihybrid cross addresses two traits and two pairs of alleles, leading to a 9:3:3:1 phenotypic ratio, as shown in larger Punnett squares.
Explanation:
The difference between a monohybrid cross and a dihybrid cross is primarily the number of traits being considered. A monohybrid cross involves organisms that are heterozygous for a single character, meaning here the cross focuses on one characteristic, such as seed color. On the other hand, a dihybrid cross involves organisms that are heterozygous for two characters, like seed color and seed shape. For instance, using Punnett squares to demonstrate a monohybrid cross, you would see a cross between parents with genotypes YY (yellow seeds) and yy (green seeds), predicting outcomes for one trait. All the resulting offspring from this cross would be Yy with yellow seeds due to yellow being the dominant allele. In contrast, the dihybrid cross involving two traits (such as AaBb for both seed color and seed shape), results in a 16-square Punnett square to determine the possible genotypes, leading to a 9:3:3:1 phenotypic ratio if both traits are independently assorting.
For example, in a dihybrid cross examining seed color (Y for yellow and y for green) and seed shape (R for round and r for wrinkled) with parents both with genotypes AaBb, the gametes could produce offspring with varying combinations of these traits, demonstrating the principle of independent assortment originally described by Mendel.
What is the difference between a monohybrid cross and a dihybrid cross? a. A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents b. A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny c. A monohybrid cross involves organisms that are heterozygous for a single character, whereas a dihybrid cross involves organisms that are heterozygous for two characters d. A monohybrid cross is performed only once, whereas a dihybrid cross is performed twice e. a monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio A monohybrid cross involves organisms that are heterozygous for a single character, whereas a dihybrid cross involves organisms that are heterozygous for two characters.