Unit 2 Test 3 Review

Each parent contributes one of two genes for a particular trait. The gene pairs are called

• variables
• hybrids
• alleles
• gametes

In mating pea plants with green pods and pea plants with yellow pods, Mendel found the F1 offspring produced only green pods. Mendel suggested that the yellow trait

• skips every other generation
• blends with the round to produce a slightly wrinkled green pod
• permanently disappears from the breeding line
• is not expressed when it is present in combination with the allele for green pods

Mendel’s principle of segregation refers to the

• separation of alleles for a particular trait during gamete formation.
• independent behavior of alleles for different traits during gamete formation.
• difference of alleles for a trait in a heterozygous genotype.
• expression of phenotype in an individual.

If homozygous red-flowered plants crossed with white-flowered plants produced all red- flowered offspring (F1 generation), the gene for red flowers must have been

• recessive
• dominant
• a multiple allele
• homozygous in the offspring

If two offspring result from the cross Aa x Aa, what is the probability that one of the offspring will have the genotype aa?

• 1/16
• 1/8
• 1/4
• 1/2

An allele that is always expressed whenever it is present is called

• dominant
• phenotypic
• recessive
• superior

The phenotype of an organism

• is used to represent its genetic composition.
• is the physical appearance of a trait.
• occurs only in dominant individuals.
• cannot be seen.

When an individual heterozygous for a trait is crossed with an individual homozygous recessive for the trait, the offspring produced will

• all have the same genotype.
• show two different phenotypes.
• show three different phenotypes.
• all have the same phenotype.

When Mendel crossed true-breeding tall plants with true-breeding short plants, all the offspring were tall because

• the allele for tall plants is recessive.
• the allele for short plants is dominant.
• the allele for tall plants is dominant.
• they were true-breeding like their parents.

Imagine two heterozygous parents. Each has a dominant allele X for brown eyes and a recessive allele x for blue eyes. The phenotypic ratio for brown:blue eyes in their children is

• 1:2:1.
• 3:1.
• 9:3:3:1.
• 1:3:1.