Complete the following practice problems.

1. A flower called the four o'clock is an example of organisms that exhibit incomplete dominance. When a red flower, RR, is crossed with a white flower, WW, the resulting offspring produces a pink flower, RW. Cross a red flower with a pink flower. Click on the blank Punnett square to check your answer.

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1. What is the probability that the offspring will have red flowers?

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   Check Your Answer

   1 over 2 1 2 or 50 percent

2. What is the probability that the offspring will have white flowers?

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   Check Your Answer

   0 percent


2. Sickle cell anemia is a codominant disorder, where N^A stands for normal red blood cells, and N^S stands for sickle-shaped red blood cells. Heterozygous individuals, N^A N^S, have a phenotype showing both sickle celled and normal shaped red blood cells. Cross two people who are heterozygous for this trait. Click on the blank Punnett square to check your answer.

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1. What is the probability that their offspring are likely to have sickle cell anemia?

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   Check Your Answer

   1 over 4 1 4 or 25 percent

2. What is the probability that their offspring will have both normal and sickle cell-shaped red blood cells?

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   Check Your Answer

   1 over 2 1 2 or 50 percent

3. What is the probability that their offspring will be able to pass along the sickle allele to their children?

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   Check Your Answer

   3 over 4 3 4 or 75 percent

3. Blood types are also controlled by multiple alleles. Look at the chart below containing blood types for the human population. Blood type A and B are both dominant while blood type O is recessive.
   

   Source: Blood in bag, Wikimedia Commons

   A man with blood type O marries a woman with blood type AB. Complete the Punnett square. Click on the blank Punnett square to check your answer.

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1. What is the probability that the parents will have a child with blood type A?

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   Check Your Answer

   1 over 2 1 2 or 50 percent

2. What is the probability that the parents will have a child with blood type O?

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   Check Your Answer

   0 percent

4. Muscular dystrophy is caused by a recessive allele located on the X chromosome. Affected people experience progressive weakening and loss of skeletal muscle. Cross a female carrier with a male that does not have Muscular dystrophy. Click on the blank Punnett square to check your answer.

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1. Is the child with MD a male or female?

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   Check Your Answer

   Male

2. From whom did this child inherit the disorder? Why?

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   Check Your Answer

   The disorder was inherited from the mother, because he got the Y from the father and the only X copy from his mother.

3. What is the probability that the couple's next child will have MD?

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   Check Your Answer

   1 over 4 1 4 or 25 percent

4. What percentage of the couple's female children will probably have MD?

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   Check Your Answer

   0 percent

5. What percentage of the couple's male children will probably have MD?

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   Check Your Answer

   1 over 2 1 2 or 50 percent