Dihybrid Cross Concepts and Applications

This video tutorial introduces dihybrid crosses, comparing them to monohybrid inheritance. It explains the inheritance of two different genes, using pea plants as an example. The tutorial covers the use of Punnett squares to determine genotypes and phenotypes of offspring, focusing on the F1 and F2 generations. The video concludes with a discussion on the phenotypic ratios observed in dihybrid crosses.

What is the main difference between monohybrid and dihybrid inheritance?

• Monohybrid inheritance involves two genes, while dihybrid involves one.

• Monohybrid inheritance involves multiple genes, while dihybrid involves a single gene.

• Monohybrid inheritance involves dominant alleles only, while dihybrid involves recessive alleles only.

• Monohybrid inheritance involves one gene, while dihybrid involves two.

In the context of dihybrid crosses, what does a 'pure breeding' seed mean?

• It has only dominant alleles for all traits.

• It has only recessive alleles for all traits.

• It has identical alleles for a specific trait.

• It has a mix of dominant and recessive alleles.

Which of the following is a dominant allele for seed color in pea plants?

• Green (y)

• Yellow (Y)

• Wrinkled (r)

• Round (R)

What is the purpose of using a Punnett square in dihybrid crosses?

• To identify the dominant and recessive alleles in parents.

• To calculate the probability of genetic mutations.

• To predict the genotypes and phenotypes of offspring.

• To determine the number of chromosomes in an organism.

In a dihybrid cross, what does the genotype 'YyRr' indicate?

• Homozygous recessive for both traits.

• Heterozygous for one trait and homozygous for the other.

• Homozygous dominant for both traits.

• Heterozygous for both traits.

What is the expected phenotype of an F1 generation from a dihybrid cross of pure breeding yellow round and green wrinkled pea plants?

• Green and round

• Yellow and wrinkled

• Yellow and round

• Green and wrinkled

What does it mean if an organism is heterozygous for a trait?

• It has two identical alleles for that trait.

• It has two different alleles for that trait.

• It has only recessive alleles for that trait.

• It has only dominant alleles for that trait.

In the F2 generation of a dihybrid cross, what is the phenotypic ratio of yellow round to green wrinkled?

• 1:1

• 3:1

• 2:1

• 9:3:3:1

How many different phenotypes are expected in the F2 generation of a dihybrid cross?

• 4

• 5

• 3

• 2

What fraction of the F2 generation in a dihybrid cross will have both recessive traits?

• 9/16

• 1/2

• 1/16

• 1/4