Ch. 12 Genetics

Suppose you want to study the inheritance pattern of flower color in a snapdragon variety. You cross a P₁ plant that has red flowers (genotype RR) with a P₂ plant that has white flowers (genotype rr) to generate plants in the F₁ generation that have pink flowers. Based on this cross, which statement is correct?

• Red is completely dominant to white.

• White is dominant to red.

• This is an example of co-dominance.

• This is an example of incomplete dominance.

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NGSS.HS-LS3-1

A 21-year-old pregnant woman has a father with Huntington’s disease, a rare dominant autosomal trait. This disease usually develops in middle age, so people carrying this trait do not find out they have this genetic disorder until midlife. What are the chances that the child she is carrying will develop the disease? (Assume that her male partner’s family has no history of the disease.)

• 10%

• 25%

• 50%

• 75%

• 100%

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

Suppose that two different groups of schmoos (an imaginary animal) live in geographically separated locations and rarely interbreed. On one occasion, a big-footed white-haired schmoo does mate with a small-footed brown-haired schmoo. Six offspring result: two big-footed schmoos with light brown hair and four small-footed schmoos with light brown hair. Which statement about the inheritance of hair color in schmoos is most likely correct?

• There is incomplete dominance.

• Brown is dominant to white.

• White is dominant to brown.

• White and brown are codominant.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

The ABO blood groups in humans are determined by a multiple-allele system in which I^A and I^B are codominant and are both dominant to I^O. If an infant born to a mother with blood type O is also type O, the biological father’s blood type can be

• Only O or A.

• Only A or B.

• Only O.

• O, A, or B.

• It is impossible to determine with the information given.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

The genetic disease blue sclera is determined by an autosomal dominant allele. The eyes of individuals with this allele have bluish sclera. These same individuals may also suffer from fragile bones and deafness. This is an example of

• incomplete dominance

• codominance

• pleiotropy