Concepts of Genetics 3Rd Edition By Robert - Test Bank

Concepts of Genetics 3Rd Edition By Robert – Test Bank

 

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Concepts of Genetics, 3e (Brooker)

Chapter 5   Extensions of Mendelian Inheritance

 

1) Genes that are not required for survival, but are likely to be beneficial to the organism, are called ________.

1. A) essential genes
2. B) lethal alleles
3. C) semilethal alleles
4. D) nonessential genes
5. E) conditional lethal alleles

 

Answer:  D

Explanation:  Are these genes harmful or essential?

Section:  05.06

Topic:  Lethal Alleles

Bloom’s:  1. Remember

Learning Outcome:  05.06.01 Describe the different types of lethal alleles.

Accessibility:  Keyboard Navigation

 

2) Alleles that cause death in a certain temperature range are examples of ________.

1. A) essential genes
2. B) lethal alleles
3. C) semilethal alleles
4. D) nonessential genes
5. E) conditional lethal alleles

 

Answer:  E

Explanation:  A phenotype that manifests its effects under certain conditions.

Section:  05.06

Topic:  Lethal Alleles

Bloom’s:  1. Remember

Learning Outcome:  05.06.01 Describe the different types of lethal alleles.

Accessibility:  Keyboard Navigation

 

 

 

3) Huntington disease in humans is an example of ________.

1. A) essential genes
2. B) lethal alleles
3. C) semilethal alleles
4. D) nonessential genes
5. E) sex linked allele

 

Answer:  B

Explanation:

Section:  05.06

Topic:  Lethal Alleles

Bloom’s:  1. Remember

Learning Outcome:  05.06.01 Describe the different types of lethal alleles.

Accessibility:  Keyboard Navigation

 

4) A heterozygote possesses a phenotype that is intermediate between the homozygous dominant and homozygous recessive phenotypes. This is most likely an example of ________.

1. A) lethal alleles
2. B) incomplete dominance
3. C) gene dosage
4. D) sex-influenced inheritance

 

Answer:  B

Explanation:  See table 5.1.

Section:  05.04

Topic:  Incomplete Dominance, Overdominance, and Codominance

Bloom’s:  1. Remember

Learning Outcome:  05.04.02 Explain the underlying molecular mechanisms of incomplete dominance, overdominance, and codominance.

Accessibility:  Keyboard Navigation

 

 

 

5) In four-o’clock plants, red flower color is dominant to white flower color. However, heterozygous plants have a pink color. If a pink-flowered plant is crossed with a white-flowered plant, what will be the phenotypic ratios of their offspring?

1. A) ¼ red, ½ pink, ¼ white
2. B) all pink
3. C) all white
4. D) ½ pink, ½ white
5. E) ½ red, ½ pink

 

Answer:  D

Explanation:  Half the offspring will inherit the recessive allele from both parents and the other half will be heterozygous.

Section:  05.04

Topic:  Incomplete Dominance, Overdominance, and Codominance

Bloom’s:  3. Apply

Learning Outcome:  05.04.01 Predict the outcome of crosses involving incomplete dominance, overdominance, and codominance.

Accessibility:  Keyboard Navigation

 

6) The coat characteristics of Siamese cats and Himalayan rabbits, where proteins in the extremities function differently than in other parts of the body, is an example of ________.

1. A) incomplete dominance
2. B) multiple allele systems
3. C) semilethal alleles
4. D) temperature-sensitive allele

 

Answer:  D

Explanation:  Different parts of the body might be at different temperatures.

Section:  05.03

Topic:  Environmental Effects on Gene Expression

Bloom’s:  2. Understand

Learning Outcome:  05.03.01 Discuss the role of the environment with regard to an individual’s traits.

Accessibility:  Keyboard Navigation

 

 

 

7) In rabbits, full coat color (C) is the dominant trait. A second allele, chinchilla (cch), is recessive to full coat color. Himalayan coat color (ch) is recessive to chinchilla and full coat colors, and albino (c) is recessive to all coat colors. If two chinchilla rabbits mate, what coat color is not possible in their offspring?

1. A) full coat color
2. B) chinchilla coat color
3. C) himalayan coat color
4. D) albino coat color
5. E) All coat colors are possible.

 

Answer:  A

Explanation:  Two recessive phenotype parents cannot have dominant allele progeny.

Section:  05.01

Topic:  Overview of Simple Inheritance Patterns

Bloom’s:  4. Analyze

Learning Outcome:  05.01.01 Compare and contrast the different types of Mendelian inheritance patterns involving single genes.

Accessibility:  Keyboard Navigation

 

8) In human blood groups, the fact that an individual can have an AB blood type is an example of ________.

1. A) incomplete dominance
2. B) incomplete penetrance
3. C) sex-influenced trait
4. D) temperature-sensitive conditional allele
5. E) codominance

 

Answer:  E

Explanation:  Alleles that make functional gene products can be codominant.  Recessive alleles often fail to make a product; hence, loss-of-function.

Section:  05.04

Topic:  Incomplete Dominance, Overdominance, and Codominance

Bloom’s:  2. Understand

Learning Outcome:  05.04.02 Explain the underlying molecular mechanisms of incomplete dominance, overdominance, and codominance.

Accessibility:  Keyboard Navigation

 

 

 

9) An individual with type A blood and an individual with type B blood mate and have offspring. What blood type is not possible in their offspring?

1. A) type O blood
2. B) type A blood
3. C) type B blood
4. D) type AB blood
5. E) All blood types are possible.

 

Answer:  E

Explanation:  A dominant phenotype can be homozygous or heterozygous.

Section:  05.04

Topic:  Incomplete Dominance, Overdominance, and Codominance

Bloom’s:  4. Analyze

Learning Outcome:  05.04.01 Predict the outcome of crosses involving incomplete dominance, overdominance, and codominance.

Accessibility:  Keyboard Navigation

 

10) At the molecular level, type A and type B blood differ in which of the following characteristics?

1. A) the antigens present on the surface of the red blood cells
2. B) the type of sugar found in each type
3. C) the antibodies that are generated against the other type of blood
4. D) All of these choices are correct.

 

Answer:  D

Explanation:  Think about the phenotype and the consequences when used in blood transfusions.

Section:  05.04

Topic:  Incomplete Dominance, Overdominance, and Codominance

Bloom’s:  2. Understand

Learning Outcome:  05.04.02 Explain the underlying molecular mechanisms of incomplete dominance, overdominance, and codominance.

Accessibility:  Keyboard Navigation

 

 

 

11) For a certain trait, a heterozygous individual has a selective advantage over a homozygous dominant or homozygous recessive individual. This is called ________.

1. A) codiminance
2. B) incomplete dominance
3. C) overdominance
4. D) incomplete penetrance
5. E) multiple allele systems

 

Answer:  C

Explanation:  Sometimes the heterozygote is more fit depending on conditions.

Section:  05.04

Topic:  Incomplete Dominance, Overdominance, and Codominance

Bloom’s:  2. Understand

Learning Outcome:  05.04.02 Explain the underlying molecular mechanisms of incomplete dominance, overdominance, and codominance.

Accessibility:  Keyboard Navigation

 

12) Sickle-cell anemia in humans is an example of ________.

1. A) codominance
2. B) incomplete penetrance
3. C) heterozygote advantage
4. D) multiple allele systems

 

Answer:  C

Explanation:  Homozygous dominant individuals are more susceptible to malaria and homozygous sickle cell can be lethal, therefore the heterozygous genotype is advantageous.

Section:  05.04

Topic:  Incomplete Dominance, Overdominance, and Codominance

Bloom’s:  2. Understand

Learning Outcome:  05.04.02 Explain the underlying molecular mechanisms of incomplete dominance, overdominance, and codominance.

Accessibility:  Keyboard Navigation

 

 

 

13) At the molecular level, which of the following best explains heterozygous advantage and overdominance?

1. A) A heterozygous individual can produce more varieties of homodimer proteins.
2. B) The alleles produce two different proteins with slightly different functions.
3. C) The proteins produced by the alleles may provide a broader range of environmental tolerance, such as temperature ranges.
4. D) Infectious organisms may recognize only a specific functional protein.
5. E) All of the answers are possibilities.

 

Answer:  E

Explanation:  Heterozygote advantage can be caused by a number of factors.

Section:  05.04

Topic:  Incomplete Dominance, Overdominance, and Codominance

Bloom’s:  2. Understand

Learning Outcome:  05.04.02 Explain the underlying molecular mechanisms of incomplete dominance, overdominance, and codominance.

Accessibility:  Keyboard Navigation

 

14) Polydactyly in humans is an example of ________.

1. A) simple Mendelian inheritance
2. B) incomplete dominance
3. C) incomplete penetrance
4. D) codominance
5. E) gene dosage

 

Answer:  C

Explanation:  Think range of phenotype; having an allele does not always mean manifestation.

Section:  05.02

Topic:  Dominant and Recessive Alleles

Bloom’s:  2. Understand

Learning Outcome:  05.02.03 Describe how traits can exhibit incomplete penetrance and vary in their expressivity.

Accessibility:  Keyboard Navigation

 

 

 

15) If a geneticist describes a trait as being 70% penetrant, what would that mean?

1. A) The expression of the trait varies by individual.
2. B) It is lethal in 30% of the individuals who have the trait.
3. C) Only 70% of the individuals who have a particular genotype express the trait.
4. D) The trait is present in 70% of the population.

 

Answer:  C

Explanation:  Remember penetrance is based on a percentage of phenotype/allele.

Section:  05.02

Topic:  Dominant and Recessive Alleles

Bloom’s:  2. Understand

Learning Outcome:  05.02.03 Describe how traits can exhibit incomplete penetrance and vary in their expressivity.

Accessibility:  Keyboard Navigation

 

16) The phenylketonuria phenotype in humans is an example of ________.

1. A) incomplete penetrance
2. B) codominance
3. C) an environmental-influenced trait
4. D) incomplete dominance
5. E) All of these choices are correct.

 

Answer:  C

Explanation:  Remember expression of a phenotype could be environment dependent.

Section:  05.03

Topic:  Environmental Effects on Gene Expression

Bloom’s:  2. Understand

Learning Outcome:  05.03.01 Discuss the role of the environment with regard to an individual’s traits.

Accessibility:  Keyboard Navigation

 

17) If an allele is dominant in one sex and recessive in another, it is an example of ________.

1. A) sex-limited inheritance
2. B) sex-influenced inheritance
3. C) incomplete dominance
4. D) simple Mendelian inheritance

 

Answer:  B

Explanation:  Remember genes can interact, and sometimes allelic relationships change.

Section:  05.05

Topic:  Sex-Influenced and Sex-Limited Inheritance

Bloom’s:  2. Understand

Learning Outcome:  05.05.01 Compare and contrast sex-influenced inheritance and sex-limited inheritance.

Accessibility:  Keyboard Navigation

18) New research indicates that male-pattern baldness is a sex-linked trait in humans because of mutations of an androgen receptor gene on the X chromosome.

 

Answer:  TRUE

Explanation:  Recent research shows a mutated androgen receptor gene present on the X chromosome contributes to male-pattern baldness.

Section:  05.05

Topic:  Sex-Influenced and Sex-Limited Inheritance

Bloom’s:  2. Understand

Learning Outcome:  05.05.01 Compare and contrast sex-influenced inheritance and sex-limited inheritance.

Accessibility:  Keyboard Navigation

 

19) A paralog ________.

1. A) is found for every gene in mammals
2. B) is only found on the X but not the Y chromosome
3. C) can explain the lack of phenotype for a gene knockout
4. D) cannot be mutated
5. E) has the same DNA sequence as the original duplicated gene

 

Answer:  C

Explanation:  Remember gene redundancy can be caused by previous gene duplication.

Section:  05.08

Topic:  Gene Interaction

Bloom’s:  2. Understand

Learning Outcome:  05.08.02 Compare and contrast epistasis, complementation, modifying genes, and gene redundancy.

Accessibility:  Keyboard Navigation

 

20) The interaction of two genes to produce a phenotype was first described by ________.

1. A) Morgan and Bridges
2. B) Mendel
3. C) Darwin
4. D) Bateson and Punnett
5. E) None of these choices are correct.

 

Answer:  D

Explanation:  Review section 5.8, “Gene Interaction.”

Section:  05.08

Topic:  Gene Interaction

Bloom’s:  1. Remember

Learning Outcome:  05.08.01 Define gene interaction.

Accessibility:  Keyboard Navigation

 

 

 

21) Epistasis is ________.

1. A) another term for overdominance
2. B) when one gene can mask the expression of a second gene
3. C) a trait that is only expressed in one sex of the species
4. D) when two dominant alleles can be expressed in the same individual
5. E) None of these choices are correct.

 

Answer:  B

Explanation:  Remember the phenotype of one gene can effect the products of a different gene.

Section:  05.08

Topic:  Gene Interaction

Bloom’s:  1. Remember

Learning Outcome:  05.08.02 Compare and contrast epistasis, complementation, modifying genes, and gene redundancy.

Accessibility:  Keyboard Navigation

 

22) In a dihybrid cross of two heterozygous individuals, you expect a 9:3:3:1 phenotypic ratio in the offspring, but observe a ratio of 9:7. What is the most likely explanation?

1. A) codominace
2. B) a sex-limited trait
3. C) simple Mendelian inheritance
4. D) incomplete penetrance
5. E) epistatic interactions of the two genes

 

Answer:  E

Explanation:  Remember that phenotype can be the result of biochemical pathways requiring 2 or more functional gene products.

Section:  05.08

Topic:  Gene Interaction

Bloom’s:  3. Apply

Learning Outcome:  05.08.03 Predict the outcome of crosses that exhibit epistasis, complementation, and gene redundancy.

Accessibility:  Keyboard Navigation

 

 

 

23) Which of the following is not correct concerning epistatic interactions?

1. A) They are often associated with enzymatic pathways.
2. B) They produce variations in the expected 9:3:3:1 ratio of a dihybrid cross.
3. C) They can result when a gene at one locus masks the expression of a gene at a different locus.
4. D) They always result in a 9:7 ratio of a dihybrid cross.
5. E) They are due to gene interactions.

 

Answer:  D

Explanation:  Numerous ratios are possible depending on the pathways.

Section:  05.08

Topic:  Gene Interaction

Bloom’s:  4. Analyze

Learning Outcome:  05.08.02 Compare and contrast epistasis, complementation, modifying genes, and gene redundancy.

Accessibility:  Keyboard Navigation

 

24) When wild-type offspring are produced from a cross between parents that both display the same recessive phenotype, this illustrates the genetic phenomenon of ________.

1. A) simple recessive alleles
2. B) incomplete penetrance
3. C) complementation
4. D) gene dosage
5. E) a spontaneous mutation

 

Answer:  C

Explanation:  Remember the recessive phenotype could be caused by homozygosity at more than one locus. Each recessive could be recessive at only 1 or 2 loci.

Section:  05.08

Topic:  Gene Interaction

Bloom’s:  2. Understand

Learning Outcome:  05.08.02 Compare and contrast epistasis, complementation, modifying genes, and gene redundancy.

Accessibility:  Keyboard Navigation

 

 

 

25) The multiple effects of a single gene on the phenotype of an organism is called ________.

1. A) epistasis
2. B) penetrance
3. C) expressivity
4. D) overdominance
5. E) pleiotropy

 

Answer:  E

Explanation:  Remember some gene products can have multiple effects on the phenotype, including lethality.

Section:  05.07

Topic:  Understanding Complex Phenotypes Caused by Mutations in Single Genes

Bloom’s:  1. Remember

Learning Outcome:  05.07.01 Explain the phenomenon of pleiotropy.

Accessibility:  Keyboard Navigation

 

26) A ________ allele encodes a protein that is made in the proper amount and functions normally.

1. A) loss-of-function
2. B) mutant
3. C) wild-type
4. D) gain-of-function
5. E) lethal

 

Answer:  C

Explanation:  Remember normal functional alleles tend to be the common ones found in nature, known as the wild-type allele.

Section:  05.02

Topic:  Dominant and Recessive Alleles

Bloom’s:  1. Remember

Learning Outcome:  05.02.01 Define wild-type allele and genetic polymorphism.

Accessibility:  Keyboard Navigation

 

 

 

27) In overdominance, the ________ genotype is beneficial over the ________ genotypes.

1. A) heterozygous; homozygous
2. B) homozygous; heterozygous
3. C) homozygous dominant; homozygous recessive
4. D) homozygous recessive; homozygous dominant
5. E) incomplete dominant; codominant

 

Answer:  A

Explanation:  Remember, sometimes selection favors the heterozygote because of disease resistance or biochemical range.

Section:  05.04

Topic:  Incomplete Dominance, Overdominance, and Codominance

Bloom’s:  2. Understand

Learning Outcome:  05.04.02 Explain the underlying molecular mechanisms of incomplete dominance, overdominance, and codominance.

Accessibility:  Keyboard Navigation

 

28) In cattle, the scurs trait follows a sex-influenced pattern of inheritance. A heterozygous male has the ________ phenotype and a heterozygous female has a ________ phenotype.

1. A) Y-linked; X-linked
2. B) nonbald; bald
3. C) X-linked; Y-linked
4. D) scurs; hornless

 

Answer:  D

Explanation:  See section 5.5, page 100.

Section:  05.05

Topic:  Sex-Influenced and Sex-Limited Inheritance

Bloom’s:  1. Remember

Learning Outcome:  05.05.01 Compare and contrast sex-influenced inheritance and sex-limited inheritance.

Accessibility:  Keyboard Navigation

 

 

 

29) If a combination of two or more genes is required to produce a specific trait, it is called a(n) ________.

1. A) overdominance
2. B) simple mendelian trait
3. C) sex-influenced trait
4. D) sex-linked trait
5. E) gene interaction

 

Answer:  E

Explanation:  Remember a phenotype can have many causes and dependencies.

Section:  05.08

Topic:  Gene Interaction

Bloom’s:  2. Understand

Learning Outcome:  05.08.01 Define gene interaction.

Accessibility:  Keyboard Navigation

 

30) In an epistatic interaction, the genes must be located on the same chromosome.

 

Answer:  FALSE

Explanation:  Remember genes can interact through their products, which are often diffusible in the cell.

Section:  05.08

Topic:  Gene Interaction

Bloom’s:  2. Understand

Learning Outcome:  05.08.02 Compare and contrast epistasis, complementation, modifying genes, and gene redundancy.

Accessibility:  Keyboard Navigation

 

31) Typically, a recessive allele increases the expression of a functional protein.

 

Answer:  FALSE

Explanation:  Remember recessiveness is often the result of loss-of-function, no useful gene product.

Section:  05.02

Topic:  Dominant and Recessive Alleles

Bloom’s:  2. Understand

Learning Outcome:  05.02.02 Explain the common underlying mechanisms for recessive and dominant alleles.

Accessibility:  Keyboard Navigation

 

 

 

32) Incomplete dominance is an example of blending of phenotypes, not genotypes.

 

Answer:  TRUE

Explanation:  Remember functional alleles might only be able to make a limited quantity of gene product.

Section:  05.04

Topic:  Incomplete Dominance, Overdominance, and Codominance

Bloom’s:  2. Understand

Learning Outcome:  05.01.02 Describe the molecular mechanisms that account for the Mendelian inheritance patterns involving single genes.; 05.04.02 Explain the underlying molecular mechanisms of incomplete dominance, overdominance, and codominance.

Accessibility:  Keyboard Navigation

 

33) Human blood groups are determined by antigens on the surface of red blood cells.

 

Answer:  TRUE

Explanation:  Products on red blood cell surfaces are important, see page 99.

Section:  05.04

Topic:  Incomplete Dominance, Overdominance, and Codominance

Bloom’s:  2. Understand

Learning Outcome:  05.04.02 Explain the underlying molecular mechanisms of incomplete dominance, overdominance, and codominance.

Accessibility:  Keyboard Navigation

 

34) Incomplete penetrance indicates that individuals who possess a dominant trait always express the trait.

 

Answer:  FALSE

Explanation:  See the definition of penetrance, page 92.

Section:  05.02

Topic:  Dominant and Recessive Alleles

Bloom’s:  2. Understand

Learning Outcome:  05.02.03 Describe how traits can exhibit incomplete penetrance and vary in their expressivity.

Accessibility:  Keyboard Navigation

 

 

 

35) Variable expressivity means that the phenotype of a trait can vary between individuals.

 

Answer:  TRUE

Explanation:  Remember expressivity is the range of the phenotype, in contrast to penetrance, which is the percentage of phenotypes seen in the sample that has the appropriate genotype.

Section:  05.02

Topic:  Dominant and Recessive Alleles

Bloom’s:  2. Understand

Learning Outcome:  05.02.03 Describe how traits can exhibit incomplete penetrance and vary in their expressivity.

Accessibility:  Keyboard Navigation

 

36) Paralogs are often functionally redundant and can compensate for the loss of either of the paralogs in a set.

 

Answer:  TRUE

Explanation:  Paralogs have their origin in gene duplication, and consequently are similar in function.

Section:  05.08

Topic:  Gene Interaction

Bloom’s:  2. Understand

Learning Outcome:  05.08.03 Predict the outcome of crosses that exhibit epistasis, complementation, and gene redundancy.

Accessibility:  Keyboard Navigation

 

37) Because loss-of-function alleles typically do not make a functional gene product, they usually follow the recessive allele inheritance pattern.

 

Answer:  TRUE

Explanation:  See Figure 5.2 and Table 5.2.

Section:  05.02

Topic:  Dominant and Recessive Alleles

Bloom’s:  2. Understand

Learning Outcome:  05.02.02 Explain the common underlying mechanisms for recessive and dominant alleles.

Accessibility:  Keyboard Navigation

 

 

 

38) Because most lethal alleles are inherited in a recessive manner, a cross between two heterozygous individuals could result in a 2:1 genotypic ratio in their surviving offspring.

 

Answer:  TRUE

Explanation:  See Section 5.6.

Section:  05.06

Topic:  Lethal Alleles

Bloom’s:  3. Apply

Learning Outcome:  05.06.02 Predict how lethal alleles may affect the outcome of a cross.

Accessibility:  Keyboard Navigation

 

39) Scurs are small horn-like growths in cattle that exhibit sex-influenced inheritance. The allele that determines scurs (Sc) is dominant in males and recessive in females. From a mating between a heterozygous male with scurs and a heterozygous female without scurs, what proportion of male offspring will lack scurs (be hornless)?

1. A) 0%
2. B) 25%
3. C) 50%
4. D) 75%
5. E) 100%

 

Answer:  B

Section:  05.02

Topic:  Sex-Influenced and Sex-Limited Inheritance

Bloom’s:  3. Apply

Learning Outcome:  05.05.02 Predict the outcome of crosses for sex-influenced inheritance.

Accessibility:  Keyboard Navigation

 

40) An experiment in which plants with the same genotype are raised under conditions that differ in soil quality could evaluate ________.

1. A) the norm of reaction
2. B) overdominance
3. C) genetic polymorphisms
4. D) gene interactions

 

Answer:  A

Section:  05.03

Topic:  Environmental Effects on Gene Expression

Bloom’s:  2. Understand

Learning Outcome:  05.03.02 Define norm of reaction.

Accessibility:  Keyboard Navigation