HS Int Sci Genetics

A generation of plants has a phenotypic ratio of 9:3:3:1. Which of these identifies the process that explains the results of this cross?

• gene flow

• crossing over

• rule of multiple alleles

• law of independent assortment

In human genetics, brown eyes (B) are dominant over blue eyes (b). A brown-eyed man is heterogeneous (Bb). He marries a blue-eyed woman. What is the probability of their child having blue eyes?

• 100%

• 75%

• 50%

• 25%

A female is homozygous for a recessive trait (rr), while the male is homozygous dominant for the same trait (RR). What percentage of their offspring would be expected to exhibit the dominant trait?

• 0 %

• 25%

• 50%

• 100%

When a plant with red flowers (C^R C^R) is crossed with a plant that has white flowers (C^w C^w), the resulting offspring has pink flowers (C^R C^w ). What mode of inheritance is observed?

• incomplete dominance

• complete dominance

• codominance

• sex-linked

Which statement best describes the relationship between an allele and a gene?

• An allele is a variation of a gene that can be expressed as a phenotype.

• 
  An allele is the part of a gene that attaches to messenger RNA molecules.

• An allele is a segment of a DNA molecule that controls replication of a gene.

• An allele is the primary protein made by a gene found in a developing embryo

The genetic material of two different individuals of the same species is analyzed. One individual has brown eyes. The other has blue eyes. Which characteristic for eye color would be the same for both individuals?

• the allele

• the DNA sequence

• the amount of pigment

• the location of the gene

The diagram shows a Punnett square of possible blood types for the offspring of two parents. Human blood type is an example of which inheritance pattern?

• recessive

• sex-linked

• codominant

• incomplete dominance

Red flower color is dominant to white flower color in rose plants. What is the expected result of a cross between two heterozygous rose plants?

• 100% red

• 75% red, 25% white

• 50% red, 50% white

• 25% red, 75% white

One parent is heterozygous for a certain trait (Dd). The other parent is homozygous dominant (DD) for that trait. What is the percent chance that an offspring from this cross will be heterozygous?

• 0%

• 25%

• 50%

• 100%

The ability to roll the tongue in humans is coded by the dominant allele R. The inability to roll the tongue is coded by the recessive allele r. A man with an RR allele combination for the trait produces a zygote with a woman with an rr allele combination for the trait. Which allele combination could occur in the zygote?

• RRrr

• rr

• Rr

• RR