Chapter 14: Mendel and the Gene Idea

A couple who are both carriers for the gene for cystic fibrosis have two children who have cystic fibrosis. What is the probability that their next child will have cystic fibrosis?
1. 0%
2. 25%
3. 50%
4. 75%
5. 100%
A couple who are both carriers for the gene for cystic fibrosis have two children who have cystic fibrosis. What is the probability that their next child will be phenotypically normal?
1. 0%
2. 25%
3. 50%
4. 75%
5. 100%
What is a genetic cross called between an individual of unknown genotype and a homozygous recessive?
1. a self cross
2. a test cross
3. a hybrid cross
4. an F1 cross
5. a dihybrid cross
In crossing a homozygous recessive with a heterozygote, what is the chance of getting an offspring with homozygous recessive phenotype?
1. 0%
2. 25%
3. 50%
4. 75%
5. 100%
In snapdragons, heterozygotes have pink flowers, whereas the two homozygotes have red flowers or white flowers. When plants with red flowers are crossed with plants with white flowers, what proportion of the offspring will have pink flowers?
1. 0%
2. 25%
3. 50%
4. 75%
5. 100%
Black fur in mice (B) is dominant to brown fur (b). Short tails (T) is dominant to long tails (t). What proportion of the progeny of the cross BbTt x BBtt will have black fur and long tails?
1. 1/16
2. 3/16
3. 6/16
4. 8/16
5. 9/16
Budgies are parakeets. Feather color is determined by two different genes that affect pigmentation. Y_B_ is green; yyB_ is blue; Y_bb is yellow and yybb is white.

A green budgie is crossed with a blue budgie. Which of the following results is NOT possible?
1. all green offspring
2. all blue offspring
3. all white offspring
4. all yellow offspring
5. All of the above are possible, but with different probabilities.
Budgies are parakeets. Feather color is determined by two different genes that affect pigmentation. Y_B_ is green; yyB_ is blue; Y_bb is yellow and yybb is white.

Two blue budgies were crossed. Over the years, they produced 22 offspring, 5 of which were white. What are the most likely genotypes for the two blue budgies?
1. yyBB and yyBB
2. yyBB and yyBb
3. yyBb and yyBb
4. yyBB and yybb
5. yyBb and yybb
Budgies are parakeets. Feather color is determined by two different genes that affect pigmentation. Y_B_ is green; yyB_ is blue; Y_bb is yellow and yybb is white.

The inheritance of color in budgies is an example of what genetic phenomenon?
1. pleiotropy
2. penetrance
3. polygenic inheritance
4. dominance
5. epistasis
What was the most significant conclusion that Gregor Mendel drew from his research?
1. There is considerable genetic variation in garden peas.
2. Traits are inherited in discrete units, one from each parent.
3. Dominant genes occur more frequently than recessive ones.
4. Genes are composed of DNA.
5. An organism that is homozygous for many recessive traits is at a disadvantage.
A couple has three children, all of whom have brown eyes and blod hair. Both parents are homozygous for brown eyes (BB), but one is a blond (rr) and the other is a redhead (Rr). What is the probability that their next child will be a brown-eyed redhead?
1. 1/16
2. 1/8
3. 1/4
4. 1/2
5. 1
A woman and her husband both show the normal phenotype for pigmentation, but both had one parent who was an albino. Albinism is an autosomal recessive trait. What is the probability that their first child will be an albino?
1. 0%
2. 25%
3. 50%
4. 75%
5. 100%
A woman and her husband both show the normal phenotype for pigmentation, but both had one parent who was an albino. Albinism is an autosomal recessive trait. If their first two children have normal pigmentation, what is the chance that their third child will be an albino?
1. 0%
2. 25%
3. 50%
4. 75%
5. 100%
A woman and her husband both show the normal phenotype for pigmentation, but both had one parent who was an albino. Albinism is an autosomal recessive trait. What is the chance that their fourth child will have a homozygous genotype?
1. 0%
2. 25%
3. 50%
4. 75%
5. 100%
A woman who belongs to blood group A and is Rh positive has a daughter who is O positive and a son who is B negative. Rh positive is a simple dominant over Rh negative. Which of the following is a possible genotype for the son?
1. IBIBrr
2. IBIBRR
3. IBiRr
4. IBirr
5. IBIBRr
A woman who belongs to blood group A and is Rh positive has a daughter who is O positive and a son who is B negative. Rh positive is a simple dominant over Rh negative. Which of the following is a possible genotype for the mother?
1. IAIARR
2. IAIARr
3. IAirr
4. IAiRr
5. IAiRR
A woman who belongs to blood group A and is Rh positive has a daughter who is O positive and a son who is B negative. Rh positive is a simple dominant over Rh negative. Which of the following is a possible phenotype for the father?
1. A negative
2. O negative
3. B negative
4. A positive
5. O positive
Given the parents AABBCc x AabbCc, assume simple dominance and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parents?
1. 1/4
2. 1/8
3. 3/4
4. 3/8
5. 1
The fact that all seven of the garden pea traits studied by Mendel obeyed the principle of independent assortment means that the
1. haploid number of garden peas is 7.
2. diploid number of garden peas is 7.
3. seven pairs of alleles determining these traits are on the same pair of homologous chromosomes.
4. seven pairs of alleles determining these traits behave as if they are on different chromosomes.
5. formation of gametes in plants is by mitosis only.
A sexually reproducing animal has two unlinked genes, one for head shape and one for tail length. Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?
1. HT
2. Hh
3. HhTt
4. T
5. tt
Which of the following is an example of polygenic inheritance?
1. pink flowers in snapdragons
2. the ABO blood groups in humans
3. sex-linkage in humans
4. white and purple color in sweet peas
5. skin pigmentation in humans
Two true-breeding stocks of garden peas are crossed. One parent had red, axial flowers, and the other had white, terminal flowers; all F1 individuals had red, axial flowers. If 1,000 F2 offspring resulted from the cross, how many of them would you expect to have red, terminal flowers? (Assume independent assortment)
1. 65
2. 190
3. 250
4. 565
5. 750
The ability of a single gene to have multiple phenotypes effects
1. incomplete dominance
2. multiple alleles
3. pleiotropy
4. epistasis
5. penetrance
Which of the following results in a phenotype of the heterozygote that differs from the phenotypes of both homozygotes.
1. incomplete dominance
2. multiple alleles
3. pleiotropy
4. epistasis
5. penetrance
Albinism is caused by a recessive autosomal allele. A man and woman, both normally pigmented, have an albino child together. For this trait, what is the genotype of the albino child?
1. homozygous dominant
2. homozygous recessive
3. heterozygous
4. hemizygous
5. unknown, because not enough information is provided.
Albinism is caused by a recessive autosomal allele. A man and woman, both normally pigmented, have an albino child together. The couple decides to have a second child. What is the probability that this child will be albino?
1. 0
2. 1/4
3. 1/2
4. 3/4
5. 1
Albinism is caused by a recessive autosomal allele. A man and woman, both normally pigmented, have an albino child together. The mother is now pregnant for a third time, and her doctor tells her she is carrying fraternal twins. What is the probability that both children will have normal pigmentation?
1. 3/4
2. 1/4
3. 1/16
4. 9/16
5. 16/16
A 9:3:3:1 phenotypic ratio is characteristic of the
1. F1 generation of a monohybrid cross
2. F2 generation of a monohybrid cross
3. F1 generation of a dihybrid cross
4. F2 generation of a dihybrid cross
5. F2 generation of a trihybrid cross
A 1:2:1 phenotypic ratio in the F2 generation of a monohybrid cross is a sign of
1. complete dominance
2. multiple alleles
3. incomplete dominance
4. polygenic inheritance
5. pleiotropy
How many unique gamete could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?
1. 4
2. 8
3. 16
4. 32
5. 1/64
In cattle, roan coat color (mixed red and white hairs) occurs in teh heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. When two roan cattle are crossed, the phenotypes of the progeny are found to be in the ratio of 1 red:2roan:1 white. Which of the following crossed could produce the highest percentages of ran cattle?
1. red x white
2. roan x roan
3. white x roan
4. red x roan
5. All of the above crosses would give the same percentages of roan.
Roan color in cattle is the result of absence of dominance between red and white color genes. How would one produce a herd of pure-breeding roan-colored cattle?
1. cross roan with roan
2. cross red with white
3. cross roan with red
4. cross roan with white
5. It cannot be done
Three babies were recently mixed up in a hospital. After consideration of the data below, which of the following represents the correct baby/parent combinations?

Couple # I II III
Blood groups A & A B & B B & O
---------------------------------------------------------------------------------
Baby # I II III
Blood groups B O AB
---------------------------------------------------------------------------
1. I-3, II-1, III-2
2. I-1, II-2, III-2
3. I-2, II-3, III-1
4. I-2, II-1, III-3
5. I-3, II-2, III-1
Tallness (T) is dominant to dwarfness (t), while red (R) flower color is dominant to white (r). The heterozygous condition results in pink (Rr) flower color. A dwarf red snapdragon is crossed with a plant homozygous for tallness and white flowers. What are the genotype and phenotype of the F1 individuals?
1. ttRr - dwarf and pink
2. ttrr - dwarf and white
3. TtRR - tall and red
4. TtRr - tall and pink
5. TTRR - tall and red
The probability that four coins will come up heads when flipped simultaneously is
1. 1/4 (0.25)
2. 1/2 (0.5)
3. 1/8 (0.125)
4. 1/16 (0.062)
5. 1/64 (0.016)
The effects of ____________________ (a recessive single gene) can be completely overcome by regulating the diet of the affected individual.
1. Huntington's disease
2. Tay-Sachs disease
3. phenylketonuria
4. hemophilia
5. sickle-cell disease
____________________ is caused by a dominant single gene defect and generally does not appear until the individual is 30 - 40 years of age.
1. Huntington's disease
2. Tay-Sachs disease
3. phenylketonuria
4. hemophilia
5. sickle-cell disease
Individuals with this ________________ are unable to metabolize gangliosides, which affects proper brain development. Affected individuals die in early infancy.
1. Huntington's disease
2. Tay-Sachs disease
3. phenylketonuria
4. hemophilia
5. sickle-cell disease
Substitution of the "wrong" amino acid in th ehemoglobin protein results in ___________ .
1. Huntington's disease
2. Tay-Sachs disease
3. phenylketonuria
4. hemophilia
5. sickle-cell disease
A man is brought to court in a paternity case. He has blood type B, Rh positive. The mother has blood group B, Rh negative. The man could never be the father of the child with which blood type?
1. AB, Rh negative
2. B, Rh negative
3. O, Rh negative
4. B, Rh positive
5. None of these choices will exclude the man from possible paternity.
A man is brought to court in a paternity case. He has blood type B, Rh positive. The mother has blood group B, Rh negative. The child's blood type is A, Rh negative. What can you say about the man's chances of being the father?
1. He is the father.
2. He might be the father.
3. He is not the father.
4. He might not be the father.
5. There is not enough information to make a decision.
A man is brought to court in a paternity case. He has blood type B, Rh positive. The mother has blood group B, Rh negative. The child's blood type is A, Rh negative. The woman's male secretary has a blood type of A, Rh positive. What can you say about his chances of being the father?
1. He is the father.
2. He might be the father.
3. He is not the father.
4. He might not be the father.
5. There is not enough information to make a decision.
In a dihybrid cross, the expected proportion of offspring showing both recessive traits is
1. 1/16
2. 3/16
3. 9/16
4. 1/4
5. 1/32
In a cross between parents who both exhibit the dominant curly- and dark-haired traits, one child has straight, light-colored hair. What is the hair genotype of the parents?
1. CCdd x ccDd
2. CcDd x CcDd
3. CcDd x ccdd
4. Ccdd x CcDd
5. CCDD x Cc Dd
In a cross AaBbCc x AaBbCc, what is the probability of producing the genotype AABBCC?
1. 1/4
2. 1/8
3. 1/16
4. 1/32
5. 1/64
Recipes are instructions on how to prepare food, just like genes are instructions the cell uses to make proteins. Using this analogy, a cookbook is analogous to
1. a nucleus.
2. a chromosome
3. a pair of homologous chromosomes
4. a gamete
5. a zygote
remember how you used to make up teams in gym class? The class would line up and count off by twos. All the students who were "ones" would be on one team and the "twos" would be the other team. This is analogous to Mendel's concept of
1. genes
2. ratios
3. dominance
4. segregation
5. a dihybrid cross
You are a choreographer who has been assigned the job of transforming the concepts of genetics into a dance. In order to depict independent assortment, you should have couple come together and move to the center of the floor, and then
1. they separate, with boys and girls going randomly to tow different sides of the floor.
2. they separate, with boys going to one side of the floor and girls to the other.
3. half the couples go to one side of the floor and half to the other side
4. a second group of couples enters from the side and combines with the first.
5. they exchange partners with a neighboring couple
Blueprints contain specific instruction for constructing a building. The room you are sitting in now was constructed by using the instructions on a set of blueprints. This relationship between blueprint and building is analogous to the relationship between
1. chromosomes and genes
2. genes and alleles
3. dominant and recessive alleles
4. segregation and independent assortment
5. genotype and phenotype
Which of the following terms is LEAST related to the others?
1. segregation
2. independent assortment
3. homologous chromosomes
4. pleiotropy
Which fo the following terms is LEAST related to the others?
1. homozygous
2. tetrad
3. recessive
4. heterozygous
5. dominant
Which of the following terms is LEAST related to the others?
1. pedigree
2. karyotype
3. amniocentesis
4. chorionic villus sampling
5. epistasis
Below are three major discoveries that led to our understanding of genetics.

1. an understanding of mitosis and meiosis.
2. an understanding of DNA structure and function
3. Mendel's realization of the particulate nature of heredity
1. 1,2,3
2. 2,3,1
3. 1,3,2
4. 3,2,1
5. 3,1,2
Skin color in a fish is inherited via a single gene with four different alleles. How many different genotypes would be possible in this system?
1. 3
2. 6
3. 8
4. 10
5. 16
Trudy plugged her new computer into a power strip that has an on/off switch. As a result, the power trip determined whether the on/off switch of the computer was functional: if the power strip is off, regardless of the position of the switch on the computer, the computer is off. If the power switch is on, the computer controls whether the computer is on or off. this is analogous to what genetic phenomenon?
1. pleiotropy
2. polygenic traits
3. dominance
4. codominance
5. epistasis
Mendel's law of segregation was nearly impossible for most biologists to understand until there was a general understanding of
1. dominance
2. meiosis
3. mitosis
4. pleiotropy
5. epistasis
Mendel's law of independent assortment was nearly impossible for most biologist to understand until there was a general understanding of
1. dominance
2. meiosis
3. mitosis
4. pleiotropy
5. epistasis