Choose the best answer.
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1 | |
A mutation in which most of the protein coding sequence of the gene is removed is most likely to be which type of allele? |
| | A) | Lethal |
| | B) | Dominant |
| | C) | Loss of function |
| | D) | Sex-limited |
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2 | |
The phenomenon where half the "normal" level of functional protein is not enough to generate a normal phenotype is called haploinsufficiency. Which of the following situations demonstrates haploinsufficiency? |
| | A) | Persons with type AB blood display both A and B antigens on their red blood cells. |
| | B) | Heterozygous and homozygous flowers in Fig 4.1 are both purple. |
| | C) | "Small eye" in mice is caused by loss of one copy of the Pax6 gene. |
| | D) | A mutation in a protein causes it to become much more active than usual. |
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3 | |
Which of the following statements about a lethal allele is NOT correct? |
| | A) | Lethal alleles are always recessive. |
| | B) | Lethal alleles may have a late age of onset. |
| | C) | Lethal alleles may be caused by mutations in essential genes. |
| | D) | Lethal alleles may affect one individual differently than another. |
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4 | |
Sarah has chronic bronchitis and frequently ends up hospitalized with pneumonia. She has no family history of cystic fibrosis, a serious recessive genetic disorder which affects the respiratory and digestive tracts. She and her husband, Greg, have one child after undergoing fertility treatments to overcome Greg's infertility. They are surprised when the child is diagnosed with cystic fibrosis and the genetic counselor tells them that they each also have the condition, which causes their bronchitis and infertility. Which of the following explanations would be a reasonable explanation of their situation? |
| | A) | There are several different alleles of cystic fibrosis, which cause differing forms of the disease. |
| | B) | Although the underlying disease is genetic, the severity of the disorder is influenced by environmental variation. |
| | C) | Cystic fibrosis displays variable expressivity. |
| | D) | All of the above. |
| | E) | None of the above. |
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5 | |
A semilethal allele is an example of which of the following extensions of Mendelian genetics? |
| | A) | Incomplete dominance |
| | B) | Incomplete penetrance |
| | C) | Variable expressivity |
| | D) | Overdominance |
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6 | |
In a rare blood type referred to as the Bombay phenotype, individuals are unable to attach the A or B antigens to their red blood cells. Individuals that are homozygous recessive for gene "H" have the Bombay phenotype and their blood type is type "O" regardless of their ABO genotype. This is an example of what extension of Mendelian inheritance? |
| | A) | Multiple alleles |
| | B) | Overdominance |
| | C) | Environmental influence |
| | D) | Epistasis |
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7 | |
Which of the following examples would NOT be consistent with a gene dosage effect? |
| | A) | Males with one normal allele for the X linked gene dystrophin are unaffected, while females (who shut off one of their two X chromosomes) with one normal allele for dystrophin may be mildly affected with muscular dystrophy. |
| | B) | Flower color in four-o-clocks seems to be incompletely dominant. |
| | C) | In fruit flies, homozygotes for an allele that produces a small amount of functional protein are severely abnormal but survive to adulthood, while homozygotes for an allele that produces no protein at all die as embryos. |
| | D) | In bees, males normally are haploid while females normally are diploid. |
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8 | |
Which of the following is the best example of overdominance? |
| | A) | Two lines of true breeding white parents produce purple flowered offspring. |
| | B) | Two lines of true breeding tomatoes that are susceptible to verticillium wilt (a fungal infection) produce offspring that are resistant to verticillium wilt. |
| | C) | Two true breeding lines, one tall and one short, produce offspring of medium height. |
| | D) | Two true breeding lines, one tall and one short, produce all tall offspring. |
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9 | |
The recessive mutant allele that causes cystic fibrosis is much more frequent in Caucasians of eastern European descent than in other populations. Some scientists believe heterozygotes must have had a survival advantage during plagues such as cholera that occasionally swept through this population. What concept does this illustrate? |
| | A) | Multiple alleles |
| | B) | Overdominance |
| | C) | Environmental influence |
| | D) | Epistasis |
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10 | |
You find a pink geranium in your flowerbed of red geraniums. Seeds from self fertilization of this plant produce ¼ red plants, ½ pink plants, and ¼ white plants. When considering the visible phenotype, which explanation is most likely? |
| | A) | The soil in which the pink plant was growing was deficient in a critical nutrient. |
| | B) | The pink plant had a new mutation, creating an allele to which the wild type "red" is incompletely dominant. |
| | C) | The pink plant had a new mutation, creating an allele which is incompletely dominant to red. |
| | D) | The pink plant had a new mutation, creating an allele which is codominant to "red". |
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11 | |
What are the possible offspring from a type A mother and a type AB father? |
| | A) | A, B, AB, and O |
| | B) | A, B, and AB |
| | C) | A and AB |
| | D) | A only |
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12 | |
In soybeans, resistance to sudden death syndrome (SDS) is inherited as a dominant condition. In some cases, individuals that are not resistant to SDS (but whose parents were) can pass the trait on to their progeny. This is an example of which of the following? |
| | A) | Overdominance |
| | B) | Incomplete penetrance |
| | C) | Incomplete dominance |
| | D) | Variable expressivity |
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13 | |
Neurofibromatosis is a condition in humans which is generally inherited in a dominant fashion. Assuming this disorder is 90% penetrant, what is the chance that a single child born to a father with neurofibromatosis and a mother known not to carry the mutation will have the disorder? |
| | A) | 90% |
| | B) | 50% |
| | C) | 45% |
| | D) | 5% |
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14 | |
In a group of fruit flies homozygous for an allele that causes a reduced number of thoracic bristles, you notice that the number of bristles varies from about half the normal number to only a few bristles. This is an example of which of the following? |
| | A) | Incomplete dominance |
| | B) | Overdominance |
| | C) | Incomplete penetrance |
| | D) | Variable expressivity |
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15 | |
You are trying to develop true breeding blue hydrangeas, but the plants in one corner of your plot consistently turn pink regardless of your mating strategy. Which of the following would you suspect? |
| | A) | Incomplete penetrance |
| | B) | Variable expressivity |
| | C) | Multiple genes affecting this trait |
| | D) | Environmental effects |
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16 | |
A trait that appears to be dominant in one sex but recessive in the other is called: |
| | A) | A sex limited trait |
| | B) | A sex influenced trait |
| | C) | A sex linked trait |
| | D) | None of the above. |
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17 | |
Which of the following could NOT be used to describe a sex limited trait: |
| | A) | This term refers to a trait controlled by a gene located on the X or Y chromosomes. |
| | B) | This is a trait that occurs more frequently in one sex than another. |
| | C) | This is an extreme example of a sex influenced trait. |
| | D) | This trait is likely to be a secondary sex characteristic. |
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18 | |
What ratio of phenotypes would you expect if you crossed a heterozygous Pea comb chicken to a heterozygous Rose comb chicken? |
| | A) | 9 walnut: 3 rose: 3 pea: 1 single |
| | B) | 1 walnut: 1 rose: 1 pea: 1 single |
| | C) | 3 walnut: 1 single |
| | D) | 3 rose: 1 pea |
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19 | |
Which of the following events is LEAST likely to occur in a cross involving epistasis by both genes? |
| | A) | A monohybrid has a different phenotype from either of the two parents. |
| | B) | Two lines of true breeding white parents produce purple flowered offspring. |
| | C) | A 9:3:3:1 ratio of F2 phenotypes is seen. |
| | D) | All of these are likely to be seen in epistatic interactions. |
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20 | |
If you establish a dihybrid cross and find an unexpected phenotypic ratio in the F2, which of the following might you suspect? |
| | A) | Epistasis |
| | B) | Multiple genes affecting your trait of interest |
| | C) | Linkage |
| | D) | All of these |
| | E) | None of these |
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21 | |
Lethal alleles violate the rules of Mendelian inheritance. |
| | A) | True |
| | B) | False |
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22 | |
Mutations may be recessive because cells can increase the amount of functional protein produced from their remaining normal allele. |
| | A) | True |
| | B) | False |
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23 | |
Essential genes produce proteins that are always required by the cell. |
| | A) | True |
| | B) | False |
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24 | |
Sex limited inheritance refers to traits that are located on the X or Y chromosome. |
| | A) | True |
| | B) | False |
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25 | |
For alleles that display incomplete dominance, the phenotypic ratio expected in the F2 generation of a monohybrid cross would be the same as the genotypic ratio. |
| | A) | True |
| | B) | False |
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26 | |
For genes which have multiple alleles, the relationships between those alleles can be a variety of types of dominant/recessive relationships. |
| | A) | True |
| | B) | False |
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27 | |
In some cases, the type of dominance relationship observed depends on how the phenotype is defined. |
| | A) | True |
| | B) | False |
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28 | |
You would expect individuals with type B blood to produce the anti-B antibody. |
| | A) | True |
| | B) | False |
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29 | |
Genes that show a dosage effect must be located on the X chromosome. |
| | A) | True |
| | B) | False |
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30 | |
A couple, both of whom display the recessive trait of albinism, are recruited for a study on the genetics of albinism. Their first child is normally pigmented, causing the scientists conducting the study to accuse the mother of infidelity and throw them out of the study. True or false, the scientists in this study are certain to have correctly accused the mother. |
| | A) | True |
| | B) | False |
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