An allele for a particular trait that is only expressed in the presence of a second copy of the same allele is called
a. dominant
b. codominant
c. incompletely dominant
d. recessive
e. pleiotropic
Answer: d. recessive
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Patterns Of Inheritance
- Consider the cross AaBbCcddEe X AABBccDDEe. If these 5 allele pairs all assort independently, then the probability that any individual offspring will have the genotype AABBccDdEe is 1 out of
- Three babies were recently mixed up in a hospital. Based on the data in the table above, the couple with blood types B and O are the actual parents of the child with blood type
- A woman with blood type O has a child with blood type O. She claims that a man named Ralph is the child's father. Her claim would be proven false if Ralph has blood type: Check all that apply.
- If two people who both have blood type AB get married, what is the probability that their second child will have blood type A?
- In rabbits there is a dominant gene "T" for long ears and its recessive allele "t" for short ears. At another gene locus, there are alleles "B" for black coat and "W" for white coat. Neither allele is dominant and BW produces a gray coat. These two allele pairs assort independently. If a gray rabbit that is heterozygous at the gene locus controlling ear length is mated with a white rabbit that is also heterozygous at the gene locus controlling ear length, what proportion of the long-eared offspring will be homozygous for that trait?
- In rabbits, there is a dominant gene "T" for long ears and its recessive allele "t" for short ears. At another gene locus, there are alleles "B" for black coat and "W" for white coat. Neither allele is dominant and BW produces a gray coat. These two allele pairs assort independently. If a gray rabbit that is heterozygous at the gene locus controlling ear length is mated with a white rabbit that is also heterozygous at the gene locus controlling ear length, what is the probability that their first offspring will be gray with long ears?
- In watermelons, the gene for green color is dominant over its allele for striped color. At another gene locus, the gene for short shape is dominant over its allele for long shape. These two allele pairs assort independently. If a plant with long, striped fruit is crossed with a plant that is heterozygous for both of these traits, what percentage of the offspring do you expect will be short and green?
- In humans, sickle-cell disease is caused by a single defective allele. If 2 people without sickle-cell disease have a daughter who has this disease, what is the probability that their next child will be a boy with sickle-cell disease?
- In mice, the allele for black fur is dominant to the allele for brown fur. If a male heterozygous black mouse is crossed with a female brown mouse, what percentage of the F1 offspring do you predict will be homozygous?
- If you are tossing a six-sided die, what is the probability of getting either a 1 or a 2 on your first toss AND your second toss?
- You toss a coin twice. Because the outcome of the first toss does not affect the outcome of the second toss, these 2 events are called
- Pedigrees are useful to geneticists because they can help determine: Check all that apply.
- A scientist has a pea plant that produces yellow-seeds. Since yellow is dominant to green, she wants to determine if the plant is homozygous or heterozygous. In order to be certain that she will get conclusive results from a single cross, she could cross it with: Check all that apply.
- Before Mendel's experiments with pea plants, which ideas formed the basis for most thinking about heredity? Check all that apply.
- Mendel performed reciprocal crosses in which he used pollen from a white-flowered plant to fertilize a purple-flowered plant and pollen from a purple-flowered plant to fertilize a white-flowered plant. What did these reciprocal crosses demonstrate?
- Achondroplasia is a common form of dwarfism caused by an autosomal dominant mutation in the fibroblast growth factor receptor 3 (FGFR3) gene. Two copies of the mutant gene are invariably fatal before or shortly after birth. If a person with achondroplasia marries a person of normal height, what is the probability that both their first child and second child will have achondroplasia?
- As a genetic counselor, you are constructing a human pedigree for a particular disease. You note that every generation shows the trait, suggesting that the trait is
- A Punnett square is generally used to
- Let R = red pigment and r = no pigment. In carnations, RR offspring make a lot of red pigment, rr offspring make no pigment and Rr offspring make a small amount of red pigment, thus appearing pink. Pink carnations are therefore an example of
- Let Y = yellow and y = green, and R = round and r = wrinkled. You cross YYRR peas with yyrr peas. All of the F1 individuals are yellow and round with a genotype of YyRr. You then perform an F2 cross and get the expected 9:3:3:1 phenotypic ratio. What proportion of the F2 plants are expected to be heterozygous for both traits?
- If you crossed flies heterozygous for the Cy allele, what phenotypes would you find in the adult F1 generation?
- In white tigers, the absence of fur pigmentation is caused by a recessive allele. This allele also causes the tigers to be cross-eyed. If two tigers heterozygous for this allele mate, what do you expect to see among the offspring?
- The genotypic ratio produced in the F2 generation is most likely
- The most likely explanation for this inheritance pattern is that the secretor trait is
- A male fruit fly has the genotype PpYYrrTt. In terms of these 4 allele pairs, how many different types of gametes can he form?