Exploring Mendelian Genetics and Punnett Squares

What does a dominant allele represent in genetic notation?

• A capital letter

• A lowercase letter

• A special symbol

• A number

What is the expected genotype of offspring from a heterozygous cross in a monohybrid cross?

• 25% homozygous dominant, 75% heterozygous

• 100% homozygous dominant

• 50% heterozygous, 50% homozygous recessive

• 100% heterozygous

In a cross between a homozygous recessive and a heterozygous organism, what percentage of offspring will be heterozygous?

• 75%

• 100%

• 50%

• 25%

If all offspring of guinea pigs are black, which parent genotype combination is impossible?

• Heterozygous by heterozygous

• Homozygous dominant by homozygous dominant

• Homozygous dominant by heterozygous

• Homozygous dominant by homozygous recessive

What is the expected phenotype ratio in a dihybrid cross involving complete dominance?

• 9:3:3:1

• 3:1

• 50% dominant: 50% recessive

• 1:2:1

What is the result of a dihybrid cross where one parent is homozygous dominant for both traits and the other is heterozygous for one trait and homozygous recessive for the other?

• 75% of offspring will express at least one dominant trait

• 100% of offspring will express at least one dominant trait

• 25% of offspring will express both recessive traits

• 50% of offspring will express both dominant traits

What is an example of codominance?

• A flower that changes color from red to white

• A flower that shows both red and white colors equally

• A flower that is either red or white

• A pink flower resulting from a red and white flower cross

What does incomplete dominance result in?

• Offspring with a mix of both parental traits

• Offspring with only the dominant trait

• Offspring with a blend, creating an intermediate phenotype

• Offspring with only the recessive trait

Which trait is an example of a polygenic trait in humans?

• Seed shape in peas

• Blood type

• Eye color

• Flower color

How can the environment influence genetic expression?

• It can alter the DNA sequence

• It can affect the phenotype by influencing gene expression

• It has no effect on genetic expression

• It can change the genetic makeup