7.1.2 Dihybrid Inheritance

• What is dihybrid inheritance?

  Inheritance of two traits
• In dihybrid inheritance, there is only one gene involved.

  False
• Mendel's laws of inheritance are fundamental principles of genetics.

  True
• To analyze dihybrid inheritance, we use Punnett squares to determine all possible genotypes and phenotypes in the offspring
• In dihybrid inheritance, the genotypes represent all possible combinations of the two traits, while the phenotypes represent the observable characteristics
• Match Mendel's laws with their definitions:

  Law of Segregation ↔️ Each allele pair separates during gamete formation.

  Law of Independent Assortment ↔️ Alleles of different genes assort independently.

  Law of Dominance ↔️ Dominant allele expresses its trait.
• The Law of Independent Assortment states that the inheritance of one trait affects the inheritance of another trait.

  False
• Steps to set up a Punnett square for a dihybrid cross:

  1️⃣ Identify the genotypes of parents

  2️⃣ Determine the gametes each parent can produce

  3️⃣ Set up a 4x4 Punnett square

  4️⃣ Fill in the genotypes of offspring
• The Law of Independent Assortment states that different genes assort independently during gamete formation.


  True
• Steps to set up a Punnett square for a dihybrid cross

  1️⃣ Identify the genotypes of parents

  2️⃣ Determine the gametes

  3️⃣ Set up the Punnett square

  4️⃣ Fill in the Punnett square
• In a Punnett square for a dihybrid cross, the gametes of one parent are placed along the top and the gametes of the other parent down the side.

  True
• The Law of Segregation states that each individual has two alleles for each trait, which separate during gamete formation
• The Law of Dominance explains why a genotype Bb expresses the dominant trait
• In a monohybrid cross, the gametes produced are of two types
• How many genotype combinations are possible in a monohybrid cross?

  4
• What is the genotype ratio in a monohybrid cross?

  1:2:1
• Compared to a monohybrid cross, a dihybrid cross has more complex genotype ratios
• What is the phenotype ratio for heterozygous parents (AaBb x AaBb) in a dihybrid cross?

  9:3:3:1
• All offspring of true-breeding parents (AABB x aabb) express dominant traits for both loci.


  True
• Steps to solve dihybrid crosses

  1️⃣ Identify parent genotypes

  2️⃣ Determine possible gamete combinations

  3️⃣ Set up and fill in the Punnett square

  4️⃣ Calculate genotype and phenotype ratios
• Match the traits with monohybrid or dihybrid crosses:

  Number of Genes ↔️ Monohybrid: 1, Dihybrid: 2

  Punnett Square Size ↔️ Monohybrid: 2x2, Dihybrid: 4x4

  Possible Phenotypes ↔️ Monohybrid: 2, Dihybrid: 4
• What does Mendel's Law of Segregation state?

  Alleles separate during gamete formation
• The Law of Dominance states that the dominant allele expresses its trait, while the recessive allele remains hidden.


  True
• What tool is used to determine possible genotypes and phenotypes in offspring?

  Punnett squares
• How many genes are involved in dihybrid inheritance?

  2
• How many possible phenotypes are there in a monohybrid cross?

  2
• What does the Law of Segregation state?

  Alleles separate during gamete formation
• According to the Law of Dominance, what happens to the recessive allele in genotype Bb?

  It remains hidden
• What type of inheritance involves two separate gene loci?

  Dihybrid inheritance
• How many possible phenotypes are there in a dihybrid cross?

  4
• What gametes can be produced from the genotype AaBb?

  AB, Ab, aB, ab
• The Punnett square for a monohybrid cross is 2x2
• Mendel's laws explain how traits are passed from parents to offspring.


  True
• What trait is expressed in genotype Bb according to the Law of Dominance?

  The B trait
• The number of alleles involved in monohybrid inheritance is 2
• Mendel's laws are fundamental principles that explain inheritance.

  True
• The Law of Dominance states that the dominant allele expresses its trait
• What does dihybrid inheritance refer to?

  Inheritance of two traits
• Mendel's laws are fundamental principles of inheritance.

  True
• The Law of Dominance states that the recessive allele remains hidden