Exam 11: The First Geneticist: Mendel and His Discoveries

In Mendel's pea plants,yellow seeds are dominant to green seeds.Purple flowers are dominant to white flowers.Use Y and y for the seed color alleles and P and p for the flower color alleles.Flower color and seed color assort independently.A plant of unknown genotype with yellow seeds and purple flowers is crossed to a plant with green seeds and white flowers.The offspring all have yellow seeds,but some have purple flowers,and some have white flowers.What is the genotype of the yellow-seeded,purple-flowered plant?

Mendel's crosses with pea plants disproved the notion that,when individuals with two different traits are mated,the genetic information blends in the offspring and is not retained as separate elements.

Crossing a true-breeding red-flowered snapdragon with a true-breeding white-flowered snapdragon produces all pink snapdragons in the F₁ generation.If F₁ individuals are crossed,what will be the ratio of phenotypes in the F₂ generation?

Hydrangeas can have either pink or blue flowers.You want to test if the flower color is influenced by the environment,such as the acidity of the soil.Design an experiment to test if soil acidity affects flower color.

Characters such as height,weight,and skin color are controlled by many genes acting together.These are examples of:

When two individuals with different traits are crossed,either the dominant or the recessive trait,and not an intermediate trait,is always seen,no matter what the organism or phenotype.

In humans,"unattached" earlobes are dominant over "attached" earlobes.Widow's-peak hairline is dominant over non-widow's-peak hairline.Use E and e for the earlobe phenotype alleles and W and w for the hairline phenotype alleles.A woman with unattached earlobes and a widow's peak and a man with attached earlobes and a widow's peak have a child.The child has attached earlobes and a non-widow's-peak hairline.What are the genotypes of the parents?

What is the basis of codominance?

When Mendel crossed plants and followed two traits (a dihybrid cross),he saw a 9:3:3:1 ratio of traits in the F₂ generation.What did he conclude?

Mendel postulated that individuals have genetic elements that exist in pairs,which determine a single phenotype.What do we now know these pairs of elements to be?

In Mendel's pea plants,yellow seeds are dominant to green seeds.If a true-breeding green-seed-producing plant is crossed to a heterozygous yellow-seed-producing plant,what percentage of offspring produces green seeds?

What is the physical basis for the independent assortment observation that Mendel made?

When Mendel crossed heterozygotes for flower color and seed color,what proportion of the offspring had both dominant phenotypes?