Human Genetics: Concepts and Applications (Lewis), 9th Edition

Chapter 5: Beyond Mendel's Law

Practice Tests

1
In familial hypercholesterolemia, individuals homozygous for the allele causing the disorder completely lack receptors on liver cells that take up cholesterol from the blood stream. Heterozygotes have one-half the number of receptors while individuals homozygous for the normal allele are phenotypically normal. This is an example of _____.
A)complete dominance
B)codominance
C)incomplete dominance
D)epistasis
2
The gene A exhibits incomplete dominance. What can we expect about the offspring from the mating of two heterozygotes?
A)a 3:1 phenotypic ratio
B)phenotypic ratios that match the genotypic ratios
C)a 2:1 phenotypic ratio
D)an equal number of homozygous dominant phenotypes as intermediate phenotypes
3
In humans, the dominance relationship between the A and B alleles of the ABO blood group gene is an example of _____.
A)complete dominance
B)incomplete dominance
C)codominance
D)epistasis
4
The relationship of the I and H genes affects the expression of the ABO blood type in the following ways: genotype HH or Hh, AB produces blood type AB while genotype hh, AB produces blood type O. This is an example of _____.
A)complete dominance
B)codominance
C)incomplete dominance
D)epistasis
5
An environmentally caused trait that appears to be inherited is called a(n) _____.
A)pleiotropic gene
B)penetrant gene
C)expressed gene
D)phenocopy
6
Two albino individuals marry and start a family. Their first child has normal pigmentation. Does this indicate infidelity and why/why not?
A)Yes, albinism is recessive and neither parent carries a pigment gene.
B)No, albinism is dominant therefore at least one of the parents is a carrier.
C)No, each parent could have a different gene causing his or her albinism (genetic heterogeneity).
D)The answer cannot be determined from the limited information given.
7
Two Mexican hairless dogs are crossed. What ratio of hairy : hairless dogs is expected in the offspring generation?
A)3 hairless : 1 hairy
B)3 hairy : 1 hairless
C)2 hairless : 1 hairy
D)cannot be predicted
8
A woman with type A blood has a child with type A blood. Which of the following men could not be the father of this child?
A)A
B)B
C)AB
D)all could be the father
9
Alleles that are both expressed in a heterozygote are _____.
A)completely dominant
B)codominant
C)incompletely dominant
D)epistatic
10
The Bombay phenotype is a result of ____ interacting genes and is an example of ____.
A)2; complete dominance
B)2; incomplete dominance
C)3; incomplete dominance
D)2; epistasis
11
Some people with polydactyly do not have any extra digits; some have an extra toe, while others have an extra finger. This situation is an example of a trait that is:
A)incompletely penetrant.
B)variably expressive.
C)both a and b
D)neither a nor b
12
Marfan Syndrome, a dominant single-gene defect, is characterized by lens dislocation, long limbs, spindly fingers, a caved-in chest, and a weakened aorta. This is an example of a(n) ____ trait.
A)multifactorial
B)pleiotropic
C)incompletely dominant
D)phenocopy
13
When a teratogen causes a birth defect that is similar to a genetic disorder, this is referred to as _____.
A)genetic heterogeneity
B)pleiotropy
C)a phenocopy
D)epistasis
14
A geneticist crosses a plant with red flowers to a plant with white flowers. The offspring include plants with red flowers (1/4), pink flowers (1/2), and white flowers (1/4). Which allele is dominant?
A)red
B)white
C)neither, they are incompletely dominant
D)neither, they are codominant
15
Which of the following blood types is not possible from two parents with type A blood?
A)A
B)O
C)B
D)All of the above are possible.
16
The term that is used to describe the severity or extent of a phenotype in an individual is called _____.
A)pleiotropy
B)penetrance
C)expressivity
D)epistasis
17
Which of the following diseases is an example of a pleiotropic condition?
A)cystic fibrosis
B)porphyria variegata
C)Leber optic atrophy
D)familial hypercholesterolemia
18
All of the following are features of mitochondrial DNA EXCEPT:
A)mutates faster than DNA in the nucleus.
B)maternal inheritance.
C)no crossing over.
D)one copy per mitochondrion.
19
If you examine a pedigree showing the transmission pattern of a mitochondrial gene mutation, which of the following statements would be false?
A)Mothers pass the gene to all offspring.
B)Fathers do not transmit the gene.
C)Only females will express the trait.
D)All of the above statements are true.
20
Only ____ transmit mitochondrial genes. Many mitochondrial disorders are ____, with mitochondria in a cell harboring different alleles.
A)males; heteroplasmic
B)males; heteromorphic
C)females; heteromorphic
D)females; heteroplasmic
21
Diseases resulting from mutations in mitochondrial genes affect _____.
A)mitochondrial protein synthesis
B)cellular energy reactions
C)both a and b
D)neither a nor b
22
You are studying a degenerative condition that appears to be passed on only from the mother of the family. Affected fathers do not pass the trait to the offspring. This suggests that the trait might be _____.
A)mitochondrial
B)lethal
C)epistatic
D)incompletely dominant
23
Consider an organism that is heterozygous for the genes Y and Z. If the two recessive alleles are on one chromosome, the genes are in _____.
A)cis
B)trans
C)the parental configuration
D)the recombinant configuration
24
The first genetic linkage map was constructed in what organism?
A)bacteria
B)yeast
C)peas
D)fruit flies
25
A ____ is a group of genes or DNA sequences that are inherited together on the same chromosome.
A)haplotype
B)genotype
C)heteroplast
D)phenotype
26
Progeny that exhibit a mixing of maternal and paternal alleles on a single chromosome are _____.
A)parentals
B)recombinants
C)haplotypes
D)mixed groups
27
If the percent recombination between A and B is 12, between A and C is 4, and between B and C is 8, then the order of the genes on the chromosome is _____.
A)A - B - C
B)B - A - C
C)A - C - B
D)C - B - A
28
Given the gene sequence ABCDE, crossing over should occur most frequently between _____.
A)A - B
B)A - C
C)A - D
D)A - E
29
A field called ____ matches phenotypes to chromosomal variants.
A)linkage maps
B)haplotypes
C)cytogenetics
D)genome wide association studies
30
____ describe(s) how several allele variants for a particular gene can exist in a given population. For example, for hair color there can be black, brown, red, blond hair, etc.
A)Complete dominance
B)Codominance
C)Incomplete dominance
D)Multiple alleles
31
____ allele combinations cause offspring to die early in development.
A)Epistatic
B)Variably expressive
C)Lethal
D)Codominant
32
____ describes an allele combination in which the heterozygous phenotype is intermediate between those of the two homozygotes (for example, pink flowers are intermediate between red flowers and white flowers). The dominant allele does not completely mask the recessive allele.
A)Complete dominance
B)Codominance
C)Incomplete dominance
D)Epistasis
33
____ describes an allele combination in which the heterozygous phenotype is distinct from, and is not an intermediate between, those of the two homozygotes (for example, AB blood type). Both alleles are equally expressed.
A)Complete dominance
B)Codominance
C)Incomplete dominance
D)Epistasis
34
A man who is homozygous for type A blood has a child with a woman who is homozygous for type B blood. What is the probability that this child will have type AB blood?
A)0%.
B)25%
C)50%
D)100%
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