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

Chapter 4: Single-Gene Inheritance

Practice Tests

1
Mendel's idea that "elementen" separate during gamete formation is called the law of _____.
A)particulate inheritance
B)dominance
C)segregation
D)independent assortment
2
The allele that masks the effects of the other is ____ and the masked allele is ____.
A)homozygous; heterozygous
B)homozygous; recessive
C)dominant; recessive
D)dominant; incomplete
3
True-breeding plants are always _____.
A)homozygous for the dominant allele
B)homozygous for the recessive allele
C)heterozygous
D)homozygous
4
A true-breeding tall plant is crossed to a true-breeding dwarf plant. The offspring in the F1 generation are all tall plants. The F1 generation is then crossed to yield a F2 generation. What is the phenotypic ratio of the F2 generation?
A)1 tall : 1 dwarf
B)3 tall : 1 dwarf
C)1 tall : 2 medium : 1 dwarf
D)all tall
5
Mendel's law of ____ states that a random assortment of maternally and paternally derived chromosomes in meiosis results in gametes that have different combinations of alleles.
A)particulate inheritance
B)dominance
C)segregation
D)independent assortment
6
Mendel's laws are explained by _____.
A)chromosome behavior in mitosis
B)chromosome behavior in meiosis
C)cytokinesis in mitosis and meiosis
D)Mendel's laws have not been explained.
7
Consider a group of 100 individuals (50 couples), all of whom carry a recessive disease allele. If 200 children were born to these couples, what percentage of the children would, theoretically, be heterozygous carriers like their parents?
A)0%
B)25%
C)50%
D)75%
8
Which genotype is normally not found in a gamete?
A)AB
B)Ab
C)aa
D)ab
9
Which of the following crosses is a test cross?
A)unknown x AA
B)unknown x Aa
C)unknown x aa
D)unknown x unknown
10
What term describes the most common expression of a particular allele combination in a population?
A)dominant
B)recessive
C)genotype
D)wild type
11
A test cross is conducted between an individual with a dominant phenotype, but unknown genotype, and a homozygous recessive individual. The phenotypes of the offspring are 50% dominant and 50% recessive. What was the genotype of the unknown parent?
A)homozygous dominant
B)homozygous recessive
C)heterozygous
D)All of the above are possible.
12
Kathy's brother has cystic fibrosis. Her husband has no family history of CF. What is the chance that Kathy's child has inherited the cystic fibrosis allele and is a carrier of the CF mutation?
A)1/2 x 1/2 = 1/4
B)1/3 x 1/2 = 1/6
C)2/3 x 1/4 = 1/6
D)2/3 x 1/2 = 1/3
13
The occurrence of affected individuals in every generation in a family suggests ____ trait.
A)an autosomal dominant
B)an autosomal recessive
C)either dominant or recessive
D)sex-linked
14
Which of the following incorrectly identifies the mode of inheritance for the given genetic disease?
A)Tay-Sachs disease - recessive
B)cystic fibrosis - recessive
C)Huntington disease - dominant
D)sickle cell - dominant
15
Consider an autosomal dominant trait. If an unaffected parent and an affected heterozygous parent are expecting, what is the chance of them having an unaffected child?
A)0%
B)25%
C)50%
D)100%
16
Two phenotypically normal individuals have an affected child. What can we conclude about the parents?
A)They both carried the disease allele.
B)They are not the parents of the child.
C)They are affected.
D)No conclusions can be drawn.
17
Relatives who have children together have a much higher risk of having children affected by a(n) ____ condition.
A)environmental
B)dominant
C)recessive
D)pedigree
18
The ____ rule of probability is useful in calculating the risk that certain individuals will inherit a particular genotype.
A)product
B)summation
C)additive
D)None of the above is correct.
19
Achondroplasia is a dominant form of dwarfism. Two affected individuals have a ____ chance of having an unaffected child.
A)0%
B)25%
C)50%
D)75%
20
An adult sibling of a person who is a known carrier of Tay-Sachs disease has a ____ chance of being a carrier. Note that a homozygous recessive individual does not survive childhood.
A)1/4
B)1/2
C)1/3
D)2/3
21
Recessive alleles _____.
A)appear to skip generations
B)have disorders that are typically more severe
C)produce symptoms at earlier ages
D)All of the above
22
Which of the following is a characteristic of an autosomal dominant trait?
A)both males and females may be affected
B)males and females transmit the disease with equal frequency
C)successive generations are affected
D)all of the above
23
In the cross AaBb x aabb, what percentage of the offspring are expected to show a dominant phenotype for both traits?
A)0%
B)25%
C)50%
D)100%
24
Two genes on the same chromosome can appear to assort independently if _____.
A)they are located very far apart from each other
B)they both display autosomal recessive inheritance
C)they both display autosomal dominant inheritance
D)the individual is heterozygous for both genes
25
Can independent assortment be demonstrated in a monohybrid cross?
A)Yes, you can observe random distribution of alleles into gametes.
B)Yes, you can observe random assortment of genes into gametes.
C)No, you must observe genes that are on the same chromosome.
D)No, you must examine the transmission of two or more genes.
26
Which of the following is an example of a cross between two dihybrids?
A)AaBb x aabb
B)AaBb x AaBb
C)aabb x AABB
D)aabb x aabb
27
Which of the following phenotypic results is expected from a cross between two dihybrids?
A)1:1:1:1 ratio
B)9:3:3:1 ratio
C)all dominant for both traits
D)all recessive for both traits
28
Mendel's ____ states that for two genes on different chromosomes, the inheritance of one does not influence the chance of inheritance for the other.
A)law of segregation
B)law of consanguinity
C)principle of a test cross
D)law of independent assortment
29
Albinism is an autosomal recessive trait. Two carriers of albinism have four children. One of their children is albino and the remaining three are normally pigmented. What is the probability that their next child will be albino?
A)0%
B)25%
C)75%
D)100%
30
Family relationships are displayed using _____.
A)Punnett squares
B)dihybrid crosses
C)pedigrees
D)karyotypes
31
A diploid individual with two identical alleles of a gene is ____, while a ____ has two different alleles of a gene.
A)homozygous; heterozygote
B)homozygous; recessive
C)dominant; recessive
D)dominant; incomplete
32
A ____ can be used to follow the transmission of alleles and is based on probability. It represents how particular genes in gametes come together, assuming they are carried on different chromosomes.
A)Punnett square
B)genotype
C)phenotype
D)karyotype
33
In pea plants, tall is dominant to short. Which of the following would be the genotype of a heterozygous tall plant?
A)TT
B)Tt
C)tt
D)AT
34
Sickle cell anemia is a recessive trait. A woman with sickle cell anemia disease has a child with a homozygous normal man (with no family history of sickle cell disease). What is the probability that this couple will have a homozygous normal child?
A)0%
B)25%
C)75%
D)100%
35
True or False. A pedigree can be inconclusive.
A)True.
B)False.
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