6.3.1 The Work of Mendel

• Who is considered the father of modern genetics?

  Gregor Mendel
• Mendel discovered that traits are inherited through discrete units called genes
• What happens to recessive genes when paired with dominant genes according to the Principle of Dominance?

  They are masked
• Match each of Mendel's principles with its description:

  Segregation ↔️ Genes exist in pairs and separate during gamete formation

  Dominance ↔️ Some genes mask recessive gene expression

  Independent Assortment ↔️ Genes for different traits are inherited separately
• The Principle of Segregation states that alleles for the same trait separate during gamete formation
• Dominant genes can mask the expression of recessive genes when both are present.


  True
• Match each of Mendel's principles with its example:

  Segregation ↔️ Alleles for flower color separate

  Dominance ↔️ Purple flowers hide white flowers

  Independent Assortment ↔️ Flower color and height are inherited separately
• What term did Mendel use to describe the units of inheritance?

  Genes
• According to the Principle of Dominance, recessive traits are always expressed.

  False
• What is the Principle of Segregation in Mendel's laws of inheritance?

  Genes separate during gamete formation
• The Principle of Independent Assortment states that genes for different traits are inherited dependently of each other.

  False
• Order Mendel's three principles of inheritance as they are commonly presented:

  1️⃣ Principle of Segregation

  2️⃣ Principle of Dominance

  3️⃣ Principle of Independent Assortment
• Mendel's principles laid the foundation for modern genetics.

  True
• What happens to genes during gamete formation according to the Law of Segregation?

  They separate into pairs
• What does the Law of Independent Assortment state about genes for different traits?

  They are inherited separately
• Which term describes the ability of a dominant gene to mask a recessive gene?

  Dominance
• The Law of Segregation states that genes exist in pairs
• Match the Mendelian principle with its description:

  Law of Segregation ↔️ Genes separate during gamete formation

  Law of Dominance ↔️ Dominant genes mask recessive genes

  Law of Independent Assortment ↔️ Genes for different traits are inherited separately
• Dominant genes always appear more frequently in a population than recessive genes.

  False
• Steps in the Law of Segregation

  1️⃣ Each parent contributes one allele

  2️⃣ Paired alleles separate during gamete formation

  3️⃣ Offspring receive one allele from each parent
• The Law of Independent Assortment implies that the inheritance of one trait affects the inheritance of another trait.

  False
• What is an example of the Law of Independent Assortment in pea plants?

  Plant height and seed color are inherited separately
• What combinations of traits can result from the independent assortment of plant height and seed color in pea plants?

  Tall/Green, Tall/Yellow, Short/Green, Short/Yellow
• In a monohybrid cross between two heterozygous plants (Bb), the offspring can have three possible genotypes.


  True
• What is the first step in creating a Punnett square?

  Identify parent genotypes
• In a monohybrid cross of heterozygous pea plants for flower color (Bb), the possible genotypes are BB, Bb, and bb.


  True
• Steps to determine phenotypes in a Punnett square for a monohybrid cross

  1️⃣ Identify the genotypes of the parents

  2️⃣ List the possible gametes for each parent

  3️⃣ Fill in the Punnett square

  4️⃣ Determine the offspring genotypes

  5️⃣ Determine the offspring phenotypes
• What phenotype appears in a pea plant with the genotype pp for flower color?

  White flowers
• The principle of segregation states that genes exist in pairs and separate during gamete formation.
• Sequence Mendel's three laws of inheritance

  1️⃣ Law of Segregation

  2️⃣ Law of Dominance

  3️⃣ Law of Independent Assortment
• What does the law of dominance state about dominant and recessive alleles?

  Dominant masks recessive
• The law of independent assortment states that genes for different traits are inherited together.

  False
• The law of independent assortment states that genes for different traits are inherited independently.
• The law of independent assortment states that genes for different traits are inherited independently during gamete formation
• Steps to construct a Punnett square

  1️⃣ Identify the genotypes of the parent organisms

  2️⃣ List the possible gametes produced by each parent

  3️⃣ Fill in the grid to show offspring genotypes

  4️⃣ Determine the phenotypes of the offspring
• In a monohybrid cross of heterozygous parents (Bb), the offspring genotypes BB, Bb, and bb are possible.


  True
• What type of cross results in a 9:3:3:1 phenotypic ratio in the offspring?

  Dihybrid cross
• What does the term 'genotype' refer to in genetics?

  Genetic makeup
• Heterozygous genotypes always express the recessive phenotype.

  False
• A recessive allele is expressed only when two copies are present in the genotype.


  True