Ecology Articles - BIOLOGY JUNCTION

Ecology Quiz

Ecology

Which two biomes are the most similar with regard to rainfall?
tundra & taiga
tundra & desert
rain forest & savanna
temperate forest & prairie
Which biome is characterized by a layer of permafrost?
taiga
savanna
chaparral
tundra
Biodiversity is greatest in which biome?
taiga
polar
rain forest
savanna
The eastern portion of the United States is dominated by what biome?
temperate forest
desert
taiga
prairie
In which biome of Africa would you find lions, giraffes, and elephants?
savanna
chaparral
desert
tropical rain forest
All the different species of an ecoystem are referred to as the:
biome
community
population
abiotic factors
Which of the following would represent an ecosystem?
A lake
A fish tank
A prairie
all of these
All the nonliving parts of an ecosystem are referred to as:
the community
biotic factors
abiotic factors
biomes
Which of the following would be a biotic factor in an ecosystem?
bacteria
soil
temperature
rainfall
The types and numbers of species in a given area is most greatly determined by the area’s:
biotic factors
precipitation
climate
biodiversity

Score =
Correct answers:

Evolution Quiz

Evolution

1. In biological terms, what is a species? a group of organisms that are similar in form and structure
  a group of organisms that can interbreed
  a group of organisms that share common features
  a group of organisms that have live in the same habitat
2. What is the Scala Naturae? an idea proposed by Darwin that suggests that all organisms share a common ancestor
  an idea proposed by Plato that suggests organisms are all evolving toward an ideal form
  an idea proposed by Aristotle that suggests that all organisms fit into an orderly scheme
  an idea proposed by Wallace that suggests that organisms change over time
3. Creationism is not accepted as a valid scientific theory because: it violates the scientific principle of natural causality
  it doesn’t offer a model to explain the diversity of life on earth
  it cannot be disproven
  all of these

birds

1. The picture of the finches is used to illustrate: phylogeny of finches
  change over time
  specialization of beaks for different diets
  natural selection
2. Which of the following was not an observation made by Darwin on his voyages: penguins use wings to paddle instead of fly
  snakes have rudimentary hind limbs
  the earth is very old
  islands had species that did not exist on the mainland

bones

1. The image illustrates: vestigial structures
  homologous structures
  the fossil record
  natural selection
2. Which of the following is an example of artificial selection: a panda’s thumb
  the breeding of dogs
  the galapagos finches
  a giraffe’s neck
3. According to the theory of evolution by natural selection, which of the following is true: random mating is necessary for evolution to occur
  variation does not exist between members of the same species
  populations will change to better fit their environment
  individuals will adapt to their environment
4. Which of the following are assumptions made with regards to the Theory of Evolution by Natural selection organisms compete with each other to survive
  variations exist among organisms
  not all organisms that are born survive to reproduce
  all of these

whale

1. The image illustrates which of the following: artificial selection
  acquired characteristics
  homologous structures
  vestigial structures
2. A panda’s thumb is considered an evolutionary contrivance because: it is assembled from wrist bones, and imperfect
  it is perfectly structured to grab leaves
  it is an structure that has no use
  none of these
3. Which of the following outcomes would you predict for a population of bacteria exposed to a new antibiotic. over many generations, the bacteria would become resistant to the antibiotic
  over a few generations, the bacteria would evolve into Archaebacteria
  over a few generations, the bacteria would become extinct
  over many generations, the bacteria would become more susceptible to the antibiotic
4. Which of the following is an example of convergent evolution: whales and sharks have similar body designs
  bees and hummingbirds have similar body designs
  bats and birds have similar body designs
  all of these
5. Why is evolution called the “unifying theory of biology” because it explains the diversity of life on the planet
  because it serves as a model to predict how organisms will change
  it serves as a model to interpret relationships between organisms on the planet
  all of these

moths

The image illustrates how peppered moths are related to other moths
how peppered moths adapted to a changing environment
how peppered moths became extinct
how peppered moths became two species

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Genetics Quiz

Chromosomes & Genetics

1. A human being has _____ autosomes and ______ sex chromosomes
23, 1
22 pairs, 1 pair
23, 23
2, 2

2. A section of chromosomes that codes for a trait can be called a(n):
nucleotide
base-pair
gene
nucleus

3. Somatic cells of a human have ____ chromosomes and are called ____
10, haploid
92, diploid
23, haploid
46, diploid

4. A person who receives an extra chromosome, could have:
Heightened intelligence
Down Syndrome
Red eyes
Polygenic traits

5. Each chromosome consists of two identical:
genes
nuclei
chromatids
bases

6. If a person receives an X and a Y chromosome, that person is:
female
male
red eyed
mentally challenged

7. Two alleles for pea plant height are designated T (tall) and t (dwarf). These alleles are found on:
genes
sex chromosomes
ribosomes
homologous chromosomes

8. An animal has 40 chromosomes in its gametes, how many chromosomes would you expect to find in this animal’s brain cells?
1
20
40
80

9. A picture of a person’s chromosomes is called a(n):
karyotype
syndrome
chromatin
fingerprint

10. During which phase of mitosis is DNA replicated?
interphase
prophase
anaphase
telophase

Score =
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Genetics Practice Test

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Genetics Practice Test

Multiple Choice
Identify the choice that best completes the statement or answers the question.

Mendel prevented self-pollination of his plants by

a.	growing only one kind of plant.
b.	preventing crossing-over.
c.	removing the anthers of the plants.
d.	removing the stigmas of the plants.

The “father” of genetics was

a.	T. A. Knight.	c.	Gregor Mendel.
b.	Hans Krebs.	d.	None of the above

Mendel obtained his P generation by allowing the plants to

a.	self-pollinate.	c.	assort independently.
b.	cross-pollinate.	d.	segregate.

What is the probability that the offspring of a homozygous dominant individual and a homozygous recessive individual will exhibit the dominant phenotype?

a.	0.25	c.	0.66
b.	0.5	d.	1.0

True-breeding pea plants always

a.	are pollinated by hand.
b.	produce offspring each of which can have multiple forms of a trait.
c.	produce offspring each of which can have only one form of a trait.
d.	are heterozygous.

The first filial (F1) generation is the result of

a.	cross-pollination among parents and the next generation.
b.	crosses between individuals of the parental generation.
c.	crosses between the offspring of a parental cross.
d.	self-fertilization between parental stock.

Which of the following is the designation for Mendel’s original pure strains of plants?

a.	P	c.	F1
b.	P1	d.	F2

F2 : F1 ::

a.	P : F1	c.	F1 : P
b.	F1 : F2	d.	dominant trait : recessive trait

The passing of traits from parents to offspring is called

a.	genetics.	c.	development.
b.	heredity.	d.	maturation.

10.

A genetic trait that appears in every generation of offspring is called

a.	dominant.	c.	recessive.
b.	phenotypic.	d.	superior.

11.

homozygous : heterozygous ::

a.	heterozygous : Bb	c.	BB : Bb
b.	probability : predicting chances	d.	homozygous : BB

12.

Mendel’s finding that the inheritance of one trait had no effect on the inheritance of another became known as the

a.	law of dominance.
b.	law of universal inheritance.
c.	law of separate convenience.
d.	law of independent assortment.

13.

To describe how traits can disappear and reappear in a certain pattern from generation to generation, Mendel proposed

a.	the law of independent assortment.
b.	the law of segregation.
c.	the law of genotypes.
d.	that the F2 generation will produce only purple flowers.

14.

The law of segregation explains that

a.	alleles of a gene separate from each other during meiosis.
b.	different alleles of a gene can never be found in the same organism.
c.	each gene of an organism ends up in a different gamete.
d.	each gene is found on a different molecule of DNA.

15.

When Mendel crossed pea plants that differed in two characteristics, such as flower color and plant height,

a.	these experiments led to his law of segregation.
b.	he found that the inheritance of one trait did not influence the inheritance of the other trait.
c.	he found that the inheritance of one trait influenced the inheritance of the other trait.
d.	these experiments were considered failures because the importance of his work was not recognized.

16.

The phenotype of an organism

a.	represents its genetic composition.
b.	reflects all the traits that are actually expressed.
c.	occurs only in dominant pure organisms.
d.	cannot be seen.

17.

If an individual has two recessive alleles for the same trait, the individual is said to be

a.	homozygous for the trait.
b.	haploid for the trait.
c.	heterozygous for the trait.
d.	mutated.

18.

An individual heterozygous for a trait and an individual homozygous recessive for the trait are crossed and produce many offspring. These offspring are likely to be

a.	all the same genotype.
b.	of two different phenotypes.
c.	of three different phenotypes.
d.	all the same phenotype.

19.

Tallness (T) is dominant over shortness (t) in pea plants. Which of the following represents the genotype of a pea plant that is heterozygous for tallness?

a.	T	c.	Tt
b.	TT	d.	tt

In humans, having freckles (F) is dominant over not having freckles (f). The inheritance of these traits can be studied using a Punnett square similar to the one shown below.

20.

Refer to the illustration above. The genotype represented in box 1 in the Punnett square would

a.	be homozygous for freckles.
b.	have an extra freckles chromosome.
c.	be heterozygous for freckles.
d.	have freckles chromosomes.

21.

Refer to the illustration above. The genotype in box 3 of the Punnett square is

a.	FF.	c.	ff.
b.	Ff.	d.	None of the above

22.

A trait that occurs in 450 individuals out of a total of 1,800 individuals occurs with a probability of

a.	0.04.	c.	0.50.
b.	0.25.	d.	0.75.

23.

How many different phenotypes can be produced by a pair of codominant alleles?

a.	1	c.	3
b.	2	d.	4

24.

Refer to the illustration above. The phenotype represented by box 1 is

a.	green, inflated.	c.	yellow, inflated.
b.	green, constricted.	d.	yellow, constricted.

25.

Refer to the illustration above. The genotype represented by box 2 is

a.	GgIi.	c.	GI.
b.	GGIi.	d.	Gi.

26.

2,000 yellow seeds : 8,000 total seeds ::

a.	1 : 6	c.	1 : 3
b.	1 : 8	d.	1 : 4

In rabbits, black fur (B) is dominant over brown fur (b). Consider the following cross between two rabbits.

27.

Refer to the illustration above. The device shown, which is used to determine the probable outcome of genetic crosses, is called a

a.	Mendelian box.	c.	genetic graph.
b.	Punnett square.	d.	phenotypic paradox.

28.

Refer to the illustration above. Both of the parents in the cross are

a.	black.
b.	brown.
c.	homozygous dominant.
d.	homozygous recessive.

29.

Refer to the illustration above. The phenotype of the offspring indicated by box 3 would be

a.	brown.
b.	black.
c.	a mixture of brown and black.
d.	The phenotype cannot be determined.

30.

Refer to the illustration above. The genotypic ratio of the F1 generation would be

a.	1:1.	c.	1:3.
b.	3:1.	d.	1:2:1.

31.

What is the expected genotypic ratio resulting from a homozygous dominant ´ heterozygous monohybrid cross?

a.	1:0	c.	1:2:1
b.	1:1	d.	1:3:1

32.

What fraction of the offspring resulting from a heterozygous ´ heterozygous dihybrid cross are homozygous recessive for both traits?

a.	9/16	c.	3/16
b.	1/4	d.	1/16

33.

What is the expected genotypic ratio resulting from a heterozygous ´ heterozygous monohybrid cross?

a.	1:2:1	c.	1:2
b.	1:3:1	d.	1:0

34.

What is the expected phenotypic ratio resulting from a homozygous dominant ´ heterozygous monohybrid cross?

a.	1:3:1	c.	2:1
b.	1:2:1	d.	1:0

35.

Refer to the illustration above. The phenotype represented by box 1 is

a.	round, yellow.	c.	wrinkled, yellow.
b.	round, green.	d.	wrinkled, green.

36.

Refer to the illustration above. The genotype represented by box 2 is

a.	RRYY.	c.	RrYy.
b.	RrYY.	d.	rrYy.

37.

Refer to the illustration above. Which of the following boxes represents the same phenotype as box 7?

a.	3	c.	5
b.	4	d.	6

38.

An organism that has inherited two of the same alleles of a gene from its parents is called

a.	hereditary.	c.	homozygous.
b.	heterozygous.	d.	a mutation.

39.

In pea plants, yellow seeds are dominant over green seeds. What would be the expected genotype ratio in a cross between a plant with green seeds and a plant that is heterozygous for seed color?

a.	1:3	c.	4:1
b.	1:2:1	d.	1:1

40.

codominance : both traits are displayed ::

a.	probability : crosses
b.	heterozygous : alleles are the same
c.	homozygous : alleles are the same
d.	Punnett square : chromosomes combine

41.

The difference between a monohybrid cross and a dihybrid cross is that

a.	monohybrid crosses involve traits for which only one allele exists, while dihybrid traits involve two alleles.
b.	monohybrid crosses involve self-pollination, while dihybrid crosses involve cross-pollination.
c.	monohybrid crosses involve one trait; dihybrid crosses involve two traits.
d.	dihybrid crosses require two Punnett squares; monohybrid crosses need only one.

42.

What fraction of the offspring resulting from a heterozygous ´ heterozygous dihybrid cross are heterozygous for both traits?

a.	9/16	c.	3/16
b.	1/4	d.	1/16

43.

A cross of two individuals for a single contrasting trait is called

a.	monohybrid.	c.	dominant.
b.	dihybrid.	d.	codominant.

Completion
Complete each statement.

44.

The transferring of pollen between plants is called ____________________.

45.

Mendel produced true-breeding strains of pea plants through the process of ____________________.

46.

When two members of the F1 generation are allowed to breed with each other, the offspring are referred to as the ____________________ generation.

47.

In heterozygous individuals, only the ____________________ allele achieves expression.

48.

The statement that the members of each pair of alleles separate when gametes are formed is known as the _________________________.

49.

Different forms of a particular gene, which Mendel called factors, are now called ____________________.

50.

The cellular process that results in the segregation of Mendel’s factors is ____________________.

51.

The portion of a DNA molecule containing the coded instructions that result in a particular characteristic of an organism is called a(n) ____________________.

52.

An organism’s ____________________ refers to the set of alleles it has inherited.

53.

The likelihood that a specific event will occur is called ____________________.

54.

Refer to the illustration above. The box labeled “X” represents the phenotype ____________________.

55.

A fractional probability of 1/2 is the same as a decimal probability of ____________________.

In pea plants, tallness (T) is dominant over shortness (t). Crosses between plants with these traits can be analyzed using a Punnett square similar to the one shown below.

56.

Refer to the illustration above. The parents shown in the Punnett square are likely to have offspring with a genotype ratio of ____________________.

57.

Refer to the illustration above. Box 2 and box ____________________ in the Punnett square represent plants that would be heterozygous for tallness.

58.

Refer to the illustration above. The phenotype of the plant that would be represented in box 4 of the Punnett square would be ____________________.

59.

Refer to the illustration above. The genotype of both parents shown in the Punnett square above is ____________________.

60.

A situation in which both alleles for a trait are expressed in a heterozygous offspring is called ____________________.

61.

A pattern of heredity in which a heterozygous individual has a phenotype that is intermediate between the phenotypes of its two homozygous parents is called _________________________.

62.

A table used to determine and diagram the results of a genetic cross is called a ____________________.

63.

In genetics, lowercase letters are usually used to indicate ____________________.

Problem

64.

In tomato plants, tallness is dominant over dwarfness and hairy stems are dominant over hairless stems. True-breeding (homozygous) plants that are tall and have hairy stems are available. True-breeding (homozygous) plants that are dwarf and have hairless stems are also available. Design an experiment to determine whether the genes for height and hairiness of stem are on the same or different chromosomes. Explain how you will be able to determine from the results whether the genes are on the same chromosome or different chromosomes, and whether they are close to each other or far apart if they are on the same chromosome. Write your answer in the space below.

65.

A scientist crossed true-breeding tall and hairy-stemmed tomato plants with true-breeding dwarf and hairless-stemmed tomato plants. He found that all of the F1 plants produced as a result of this cross were tall and hairy-stemmed. He then allowed the F1 plants to pollinate each other and obtained 1000 F2 plants. Of these 1000 F2 plants, he observed the following numbers of four different phenotypes:

557 tall and hairy-stemmed plants	192 dwarf and hairy-stemmed plants
180 tall and hairless-stemmed plants	71 dwarf and hairless-stemmed plants

Write your answers to the following in the space below or on a separate sheet of paper.

a.      Which height characteristic is dominant, tallness or dwarfness?
b.      Which stem characteristic is dominant, hairiness or hairlessness?
c.      What are the genotypes of the original, true-breeding parents? (Be sure to indicate what the symbols you use stand for.)
d.      What are the genotypes of the F1 hybrid plants? (Be sure to indicate what the symbols you use stand for.)
e.      What are the genotypes of the four types of plants found in the F2 generation? (Be sure to indicate what the symbols you use stand for.)
f.      What were the expected numbers of plants of each type in the F2 generation? (Round off to the nearest whole numbers.)
g.      Why did the observed numbers of plants of each type in the F2 generation differ from the expected?
h.      How could this experiment have been changed to obtain numbers of plants of each type in the F2 generation that were closer to the expected numbers?

Essay

66.

How might you go about determining the genotype of a red-flowering plant where red is dominant over white? Write your answer in the space below.

67.

Describe pollination in pea plants. Write your answer in the space below.

68.

In what ways did Mendel’s methods help ensure his success in unraveling the mechanics of heredity? Write your answer in the space below.

69.

What conclusions did Gregor Mendel reach based on his observations of pea plants? Write your answer in the space below.

70.

Describe Mendel’s observation regarding independent assortment. Write your answer in the space below.

71.

What are three ways to express the probability of an event that occurs 500 times out of 2,000 total trials? Write your answer in the space below.

72.

Describe how genotype and phenotype are related, and give an example. Write your answer in the space below.

73.

Explain what is meant by homozygous and heterozygous, and give an example of each. Write your answer in the space below.

74.

All of the offspring resulting from a cross between a red snapdragon and a white snapdragon are pink. What is a possible explanation for this? Write your answer in the space below.

Biomes of the World

Find each term and then number and define it on the back of this sheet.

ABIOTIC	BIOME	BIOTIC
CARNIVORE	CONSUMER	DECIDUOUS
DESERT	FRESHWATER	GRASSLAND
HERBIVORE	INTERTIDAL	MARINE
OMNIVORE	PRODUCER	RAINFOREST
SAVANNA	TAIGA	TUNDRA

Genetics

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Genetics

Modified True/False
Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true.

Mendel discovered predictable patterns in the inheritance of traits. _________________________

Garden peas are difficult to grow because they mature slowly. _________________________

When Mendel cross-pollinated two varieties from the P generation that exhibited contrasting traits, he called the offspring the second filial, or F2, generation. _________________________

The contrasting forms of each character studied by Mendel appeared in a 3:1 ratio in the F2 generation. _________________________

A dominant allele masks the effect of a recessive allele. _________________________

The allele for a recessive trait is usually represented by a capital letter. _________________________

Heterozygous individuals have two of the same alleles for a particular gene. _________________________

The inheritance of sex-linked traits can be studied by making a pedigree of several generations of a family. _________________________

Refer to the illustration above. The father listed in the pedigree is most likely heterozygous for the trait. _________________________

10.

Refer to the illustration above. Child #3 probably has the dominant phenotype. _________________________

11.

Albinism is caused by a recessive allele. _________________________

12.

The phenotype that results from an inherited pair of alleles depends on the instructions in the genes only. _________________________

13.

Traits for different characters that are usually inherited together are said to be combined. _________________________

Multiple Choice
Identify the choice that best completes the statement or answers the question.

14.

The passing of traits from parents to offspring is called

a.	genetics.	c.	development.
b.	heredity.	d.	maturation.

15.

The difference between Mendel’s experiments in the area of heredity and those done by earlier researchers was that

a.	earlier researchers did not have microscopes.
b.	earlier researchers used detailed and numerical procedures.
c.	Mendel expressed the results of his experiments in terms of numbers.
d.	Mendel used pea plants with both purple and white flowers.

16.

The scientific study of heredity is called

a.	meiosis.	c.	genetics.
b.	crossing-over.	d.	pollination.

17.

The “father” of genetics was

a.	A. Knight.	c.	Gregor Mendel.
b.	Hans Krebs.	d.	Charles Darwin.

18.

Garden peas are good subjects for studying heredity because they

a.	are difficult to grow.	c.	produce few offspring.
b.	mature quickly.	d.	have few traits.

19.

Mendel obtained his P generation by allowing the plants to

a.	self-pollinate.	c.	assort independently.
b.	cross-pollinate.	d.	segregate.

20.

Step 1 of Mendel’s garden pea experiment, allowing each variety of garden pea to self-pollinate for several generations, produced the

a.	F1 generation.	c.	P generation.
b.	F2 generation.	d.	P1 generation.

21.

F2 : F1 ::

a.	P : F1	c.	F1 : P
b.	F1 : F2	d.	P : F2

22.

An allele that is always expressed whenever it is present is called

a.	dominant.	c.	recessive.
b.	phenotypic.	d.	superior.

23.

The discovery of chromosomes provided a link between the first law of heredity that stemmed from Mendel’s work and

a.	pollination.	c.	mitosis.
b.	inheritance.	d.	meiosis.

24.

The law of segregation states that

a.	alleles of a gene separate from each other during meiosis.
b.	different alleles of a gene can never be found in the same organism.
c.	each gene of an organism ends up in a different gamete.
d.	each gene is found on a different molecule of DNA.

25.

Mendel’s law of segregation states that

a.	pairs of alleles are dependent on one another when separation occurs during gamete formation.
b.	pairs of alleles separate independently of one another after gamete formation.
c.	each pair of alleles remains together when gametes are formed.
d.	the two alleles for a trait segregate independently when gametes are formed.

26.

The phenotype of an organism

a.	is used to represent its genetic composition.
b.	is the physical appearance of a trait.
c.	occurs only in dominant individuals.
d.	cannot be seen.

27.

If an individual possesses two recessive alleles for the same trait, the individual is said to be

a.	homozygous for the trait.	c.	heterozygous for the trait.
b.	haploid for the trait.	d.	mutated.

28.

When an individual heterozygous for a trait is crossed with an individual homozygous recessive for the trait, the offspring produced will

a.	all have the same genotype.
b.	show two different phenotypes.
c.	show three different phenotypes.
d.	all have the same phenotype.

29.

Tallness (T) is dominant to shortness (t) in pea plants. Which of the following represents a genotype of a pea plant that is heterozygous for tallness?

a.	T	c.	Tt
b.	TT	d.	tt

30.

homozygous : heterozygous ::

a.	heterozygous : Bb	c.	probability : chance
b.	gg : Gg	d.	factor : gene

31.

Mendel’s finding that the inheritance of one trait had no effect on the inheritance of another became known as the

a.	law of dominance.
b.	law of universal inheritance.
c.	law of separate convenience.
d.	law of independent assortment.

In humans, having freckles (F) is dominant to not having freckles (f). The inheritance of these traits can be studied using a Punnett square similar to the one shown below.

32.

Refer to the illustration above. The child represented in box 1 in the Punnett square would

a.	be homozygous for freckles.
b.	have an extra freckles chromosome.
c.	be heterozygous for freckles.
d.	not have freckles.

33.

Refer to the illustration above. The parents shown in the Punnett square could have children with a phenotype ratio of

a.	1:2:1.	c.	3:1.
b.	4:0.	d.	2:2.

34.

Refer to the illustration above. Which box in the Punnett square represents a child who does not have freckles?

a.	box 1	c.	box 3
b.	box 2	d.	box 4

35.

Refer to the illustration above. The child in box 3 of the Punnett square has the genotype

a.	FF.	c.	ff.
b.	Ff.	d.	FfFf.

In rabbits, black fur (B) is dominant to brown fur (b). Consider the following cross between two rabbits.

36.

Refer to the illustration above. The device shown, which is used to determine the probable outcome of genetic crosses, is called a

a.	Mendelian box.	c.	genetic graph.
b.	Punnett square.	d.	phenotypic paradox.

37.

Refer to the illustration above. Both of the parents in the cross are

a.	black.	c.	homozygous dominant.
b.	brown.	d.	homozygous recessive.

38.

Refer to the illustration above. The phenotype of the offspring indicated by box 3 would be

a.	brown.	c.	a mixture of brown and black.
b.	black.	d.	white.

39.

Refer to the illustration above. The genotypic ratio of the F1 generation would be

a.	1:1.	c.	1:3.
b.	3:1.	d.	1:2:1.

40.

What is the expected genotypic ratio resulting from a homozygous dominant ´ heterozygous monohybrid cross?

a.	1:0	c.	1:2:1
b.	1:1	d.	1:3:1

41.

What is the expected genotypic ratio resulting from a heterozygous ´ heterozygous monohybrid cross?

a.	1:2:1	c.	1:2
b.	1:3:1	d.	1:0

42.

What is the expected phenotypic ratio resulting from a homozygous dominant ´ heterozygous monohybrid cross?

a.	1:3:1	c.	2:1
b.	1:2:1	d.	1:0

43.

The unknown genotype of an individual with a dominant phenotype can be determined using a

a.	ratio.	c.	probability formula.
b.	dihybrid cross.	d.	test cross.

44.

What is the probability that the offspring of a homozygous dominant individual and a homozygous recessive individual will exhibit the dominant phenotype?

a.	0.25	c.	0.66
b.	0.5	d.	1.0

45.

Probability is calculated by dividing the number of one kind of possible outcome by the

a.	number of other kinds of outcomes.
b.	total number of all possible outcomes.
c.	number of genes being considered.
d.	total number of offspring produced.

46.

If a characteristic is sex-linked, the gene for it is found on

a.	a sex chromosome.	c.	a linked chromosome.
b.	an autosome.	d.	an allele.

47.

Since the allele for colorblindness is located on the X chromosome, colorblindness

a.	cannot be inherited.	c.	is sex-linked.
b.	occurs only in adults.	d.	occurs only in females.

48.

A diagram in which several generations of a family and the occurrence of certain genetic characteristics are shown is called a

a.	Punnett square.	c.	pedigree.
b.	monohybrid cross.	d.	family karyotype.

49.

In humans, eye color and height are controlled by

a.	simple dominance.	c.	polygenic inheritance.
b.	multiple alleles.	d.	incomplete dominance.

50.

Which of the following traits is controlled by multiple alleles in humans?

a.	eye color	c.	colorblindness
b.	blood type	d.	albinism

51.

What would be the blood type of a person who inherited an A allele from one parent and an O allele from the other?

a.	type A	c.	type AB
b.	type B	d.	type O

52.

Which of the following is not an outcome of the environment modifying a phenotype?

a.	the changing of the color of an animal’s fur as the temperature changes
b.	the increased intelligence of a person who attended school for many years
c.	the very short stature of a kind of tree that grows at a high altitude in comparison with the same kind of tree growing at a lower altitude
d.	the pink-flowered snapdragons that result from crosses between red-flowered and white-flowered snapdragon plants

53.

Genes that are close together on a single chromosome are considered to be

a.	alleles.	c.	independent.
b.	homozygous.	d.	linked.

Genetics Tutorial

Name:

Human Genetics Web Tutorial

True/False

Indicate whether the sentence or statement is true or false.

Hemophilia is a recessive, sex-linked disorder.

An autosomal trait will occur with equal frequency in both males and females.

Sex-linkd traits appear more often in females than in males.

An individual who expresses a genetic disorder is called a carrier.

A male can produce sperm that contains either an X or a Y chromosome.

Mutations are always harmful.

A pedigree is a family record that shows how a trait is inherited over several generations.

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

Hemophilia is a genetic disorder that is

a.	sex-linked.	c.	fairly common.
b.	sex-influenced.	d.	more common in women than in men.

Parents of a color blind female could have the genotypes

a.	XCXc and XCY	c.	XCXc and XcY
b.	XcXc and XCY	d.	XCXC and XcY

10.

People who are heterozygous for sickle cell anemia are

a.	partially resistant to the effect of ultraviolet radiation.
b.	totally resistant to the effect of ultraviolet radiation.
c.	partially resistant to malaria.
d.	totally resistant to malaria.

11.

Both sickle cell anemia and hemophilia

a.	are caused by genes coding for defective proteins.
b.	are seen in homozygous dominant individuals.
c.	provide resistance to malaria infections.
d.	are extremely common throughout the world.

12.

This genetic disease occurs most frequently in the black population.

a.	cystic fibrosis	c.	sickle-cell anemia
b.	Tay-Sachs disease	d.	hemophilia

13.

The trait for skin color in humans is cause by

a.	crossing-over	c.	nondisjunction
b.	multiple genes	d.	mutations

14.

A hereditary disease in which the red blood cells have an abnormal shape is

a.	galactosemia	c.	polydactyly
b.	Tay-Sachs disease	d.	sickle-cell anemia

15.

Sex-linked traits appear more often in males than in females because

a.	males are produced in greater numbers
b.	females with a sex-linked trait will die
c.	males have only one X chromosome
d.	sex-linked traits are carried on the Y chromosome

16.

A diagram in which several generations of a family and the occurrence of certain genetic characteristics are shown is called a

a.	Punnett square.	c.	pedigree.
b.	monohybrid cross.	d.	family karyotype.

17.

What is the percentage of chance that two people who carry a sickle-cell gene will have a child having the disease?

a.	0	c.	50
b.	25	d.	100

18.

Which genetic trait is most influenced by the environment?

a.	blood type	c.	baldness
b.	eye color	d.	weight

19.

Very dark-skinned people have alleles at all gene positions for skin color that code for

a.	red-green colorblindness.	c.	the production of Rh antigens.
b.	albinism.	d.	the production of melanin.

20.

Sex-linked traits such as color blindness

a.	are never carried by females	c.	occur more frequently in males
b.	occur more frequently in females	d.	never occur in males

21.

What would be the blood type of a person who inherited an A allele from one parent and an O allele from the other?

a.	type A	c.	type AB
b.	type B	d.	type O.

22.

Genetic counseling is a process that

a.	helps identify parents at risk for having children with genetic defects.
b.	assists parents in deciding whether or not to have children.
c.	uses a family pedigree.
d.	All of the above

23.

If both parents carry the recessive allele that causes cystic fibrosis, the chance that their child will develop the disease is

a.	one in two.	c.	two in five.
b.	one in four.	d.	100 percent.

24.

People with Down syndrome have

a.	45 chromosomes.	c.	47 chromosomes.
b.	46 chromosomes.	d.	no X chromosomes.

25.

If nondisjunction occurs,

a.	there will be too many gametes produced.
b.	no gametes will be produced.
c.	a gamete will receive too many or too few homologues of a chromosome.
d.	mitosis cannot take place.

26.

A human female inherits

a.	one copy of every gene located on each of the X chromosomes.
b.	twice as many sex chromosomes as a human male inherits.
c.	one copy of every gene located on the Y chromosome.
d.	all of the same genes that a human male inherits.

27.

A pedigree CANNOT be used to

a.	determine whether a trait is inherited.
b.	show how a trait is passed from one generation to the next.
c.	determine whether an allele is dominant or recessive.
d.	none of the above

28.

If a man with blood type A and a woman with blood type B produce an offspring, what might be the offspring’s blood type?

a.	AB or O
b.	A, B, or O
c.	A, B, AB, or O
d.	AB only

29.

Sickle cell disease is caused by a

a.	change in one DNA base.
b.	change in the size of a chromosome.
c.	change in two genes.
d.	change in the number of chromosomes in a cell.

30.

Many sex-linked genes are located on

a.	the autosomes.
b.	the X chromosome only.
c.	the Y chromosome only.
d.	both the X chromosome and the Y chromosome.

Genetics Practice Test Bi

Chapter 9 Test, Form A

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

The “father” of genetics was

a.	T. A. Knight.	c.	Gregor Mendel.
b.	Hans Krebs.	d.	None of the above

Mendel obtained his P generation by allowing the plants to

a.	self-pollinate.	c.	assort independently.
b.	cross-pollinate.	d.	segregate.

What is the probability that the offspring of a homozygous dominant individual and a homozygous recessive individual will exhibit the dominant phenotype?

a.	0.25	c.	0.66
b.	0.5	d.	1.0

True-breeding pea plants always

a.	are pollinated by hand.
b.	produce offspring with either form of a trait.
c.	produce offspring with only one form of a trait.
d.	are heterozygous.

The first filial (F1) generation is the result of

a.	cross-pollination among parents and the next generation.
b.	crosses between individuals of the parental generation.
c.	crosses between the offspring of a parental cross.
d.	self-fertilization between parental stock.

Which of the following is the designation for Mendel’s original pure strains of plants?

a.	P	c.	F1
b.	P1	d.	F2

A genetic trait that appears in every generation of offspring is called

a.	dominant.	c.	recessive.
b.	phenotypic.	d.	superior.

To describe how traits can disappear and reappear in a certain pattern from generation to generation, Mendel proposed

a.	the law of independent assortment.
b.	the law of segregation.
c.	the law of genotypes.
d.	that the F2 generation will only produce purple flowers.

When Mendel crossed pea plants with two contrasting traits, such as flower color and plant height,

a.	these experiments led to his law of segregation.
b.	he found that the inheritance of one trait did not influence the inheritance of the other trait.
c.	he found that the inheritance of one trait influenced the inheritance of the other trait.
d.	these experiments were considered failures because the importance of his work was not recognized.

10.

If an individual has two recessive alleles for the same trait, the individual is said to be

a.	homozygous for the trait.	c.	heterozygous for the trait.
b.	haploid for the trait.	d.	mutated.

11.

An individual heterozygous for a trait and an individual homozygous recessive for the trait are crossed and produce many offspring that are

a.	all the same genotype.	c.	of three different phenotypes.
b.	of two different phenotypes.	d.	all the same phenotype.

In humans, having freckles (F) is dominant to not having freckles (f). The inheritance of these traits can be studied using a Punnett square similar to the one shown below.

12.

Refer to the illustration above. The genotype represented in box “1” in the Punnett square would

a.	be homozygous for freckles.
b.	have an extra freckles chromosome.
c.	be heterozygous for freckles.
d.	have freckles chromosomes.

13.

Refer to the illustration above. The genotype in box “3” of the Punnett square is

a.	FF.	c.	ff.
b.	Ff.	d.	None of the above

14.

How many different phenotypes can be produced by a pair of codominant alleles?

a.	1	c.	3
b.	2	d.	4

15.

Refer to the illustration above. The phenotype represented by the cell labeled “1” is

a.	green, inflated.	c.	yellow, inflated.
b.	green, constricted.	d.	yellow, constricted.

16.

2,000 yellow seeds : 8,000 total seeds ::

a.	1 : 6	c.	1 : 3
b.	1 : 8	d.	1 : 4

In rabbits, black fur (B) is dominant to brown fur (b). Consider the following cross between two rabbits.

17.

Refer to the illustration above. Both of the parents in the cross are

a.	black.	c.	homozygous dominant.
b.	brown.	d.	homozygous recessive.

18.

Refer to the illustration above. The phenotype of the offspring indicated by box “3” would be

a.	brown.	c.	a mixture of brown and black.
b.	black.	d.	The phenotype cannot be determined.

19.

What is the expected phenotypic ratio resulting from a homozygous dominant ´ heterozygous monohybrid cross?

a.	1:3:1	c.	2:1
b.	1:2:1	d.	1:0

20.

Refer to the illustration above. The phenotype represented by the cell labeled “1” is

a.	round, yellow.	c.	wrinkled, yellow.
b.	round, green.	d.	wrinkled, green.

21.

An organism that has inherited two of the same alleles of a gene from its parents is called

a.	hereditary.	c.	homozygous.
b.	heterozygous.	d.	a mutation.

22.

In pea plants, yellow seeds are dominant over green seeds. What would be the expected genotype ratio in a cross between a plant with green seeds and a plant that is heterozygous for seed color?

a.	1:3	c.	4:1
b.	1:2:1	d.	1:1

23.

codominance : both traits are displayed ::

a.	probability : crosses
b.	heterozygous : alleles are the same
c.	homozygous : alleles are the same
d.	Punnett square : chromosomes combine

24.

The difference between a monohybrid cross and a dihybrid cross is that

a.	monohybrid crosses involve traits for which only one allele exists, while dihybrid traits involve two alleles.
b.	monohybrid crosses involve self-pollination, while dihybrid crosses involve cross-pollination.
c.	monohybrid crosses involve one gene; dihybrid crosses involve two genes.
d.	dihybrid crosses require two Punnett squares; monohybrid crosses need only one.

25.

What fraction of the offspring resulting from a heterozygous ´ heterozygous dihybrid cross are heterozygous for both traits?

a.	9/16	c.	3/16
b.	1/4	d.	1/16

AP Heredity Study Guide

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Name:

ap heredity study guide

Multiple Choice
Identify the choice that best completes the statement or answers the question.

Pea plants were particularly well suited for use in Mendel’s breeding experiments for all of the following reasons except that

a.	peas show easily observed variations in a number of characters, such as pea shape and flower color.
b.	it is possible to completely control matings between different pea plants.
c.	it is possible to obtain large numbers of progeny from any given cross.
d.	peas have an unusually long generation time.
e.	many of the observable characters that vary in pea plants are controlled by single genes.

A plant with purple flowers is allowed to self-pollinate. Generation after generation, it produces purple flowers. This is an example of

a.	hybridization.
b.	incomplete dominance.
c.	true-breeding.
d.	the law of segregation.
e.	polygenetics.

Which of the following statements about Mendel’s breeding experiments is correct?

a.	None of the parental (P) plants were true-breeding.
b.	All of the F2 progeny showed a phenotype that was intermediate between the two parental (P) phenotypes.
c.	Half of the F1 progeny had the same phenotype as one of the parental (P) plants, and the other half had the same phenotype as the other parent.
d.	All of the F1 progeny resembled one of the parental (P) plants, but only some of the F2 progeny did.
e.	none of the above

What is the difference between a monohybrid cross and a dihybrid cross?

a.	A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents.
b.	A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny.
c.	A monohybrid cross involves organisms that are heterozygous for a single character, whereas a dihybrid cross involves organisms that are heterozygous for two characters.
d.	A monohybrid cross is performed only once, whereas a dihybrid cross is performed twice.
e.	A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio.

A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates

a.	the blending model of genetics.
b.	true-breeding.
c.	dominance.
d.	a dihybrid cross.
e.	the mistakes made by Mendel.

The F1 offspring of Mendel’s classic pea cross always looked like one of the two parental varieties because

a.	one allele was completely dominant over another.
b.	each allele affected phenotypic expression.
c.	the traits blended together during fertilization.
d.	no genes interacted to produce the parental phenotype.
e.	different genes interacted to produce the parental phenotype.

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?

a.	There is considerable genetic variation in garden peas.
b.	Traits are inherited in discrete units, and are not the results of “blending.”
c.	Recessive genes occur more frequently in the F1 than do dominant ones.
d.	Genes are composed of DNA.
e.	An organism that is homozygous for many recessive traits is at a disadvantage.

Which of the following is (are) true for alleles?

a.	They can be identical or different for any given gene in a somatic cell.
b.	They can be dominant or recessive.
c.	They can represent alternative forms of a gene.
d.	Only A and B are correct.
e.	A, B, and C are correct.

What is genetic cross between an individual showing a dominant phenotype (but of unknown genotype) and a homozygous recessive individual called?

a.	a self-cross
b.	a testcross
c.	a hybrid cross
d.	an F1 cross
e.	a dihybrid cross

10.

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?

a.	4
b.	8
c.	16
d.	32
e.	64

11.

Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This suggests

a.	that the parents were true-breeding for contrasting traits.
b.	incomplete dominance.
c.	that a blending of traits has occurred.
d.	that the parents were both heterozygous.
e.	that each offspring has the same alleles.

12.

Two characters that appear in a 9:3:3:1 ratio in the F2 generation should have which of the following properties?

a.	Each of the characters is controlled by a single gene.
b.	The genes controlling the characters obey the law of independent assortment.
c.	Each of the genes controlling the characters has two alleles.
d.	Only A and C are correct.
e.	A, B, and C are correct.

13.

A 9:3:3:1 phenotypic ratio is characteristic of which of the following?

a.	a monohybrid cross
b.	a dihybrid cross
c.	a trihybrid cross
d.	linked genes
e.	both A and D

14.

A sexually reproducing animal has two unlinked genes, one for head shape (H). and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?

a.	HT
b.	Hh
c.	HhTt
d.	T
e.	tt

15.

It was important that Mendel examined not just the F1 generation in his breeding experiments, but the F2 generation as well, because

a.	he obtained very few F1 progeny, making statistical analysis difficult.
b.	parental traits that were not observed in the F1 reappeared in the F2, suggesting that the traits did not truly disappear in the F1.
c.	analysis of the F1 progeny would have allowed him to discover the law of segregation, but not the law of independent assortment.
d.	the dominant phenotypes were visible in the F2 generation, but not in the F1.
e.	all of the above

16.

When crossing a homozygous recessive with a heterozygote, what is the chance of getting an offspring with the homozygous recessive phenotype?

a.	0%
b.	25%
c.	50%
d.	75%
e.	100%

Use the diagram and description below to answer the following question.

In a particular plant, leaf color is controlled by gene D. Plants with the dominant allele D have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of this cross is diagrammed in the Punnett square shown below, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square.

17.

Which of the boxes marked 1-4 correspond to plants with dark leaves?

a.	1 only
b.	1 and 2
c.	2 and 3
d.	4 only
e.	1, 2, and 3

18.

Which of the boxes correspond to plants with a heterozygous genotype?

a.	1
b.	1 and 2
c.	1, 2, and 3
d.	2 and 3
e.	2, 3, and 4

19.

Which of the plants will be true-breeding?

a.	1 and 4
b.	2 and 3
c.	1-4
d.	1 only
e.	none

20.

P = purple, pp = white. The offspring of a cross between two heterozygous purple-flowering plants (Pp Pp) results in

a.	all purple-flowered plants.
b.	purple-flowered plants and white-flowered plants.
c.	two types of white-flowered plants: PP and Pp.
d.	all white-flowered plants.
e.	all pink-flowered plants.

21.

Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that

a.	new mutations were frequently generated in the F2 progeny, “reinventing” traits that had been lost in the F1.
b.	the mechanism controlling the appearance of traits was different between the F1 and the F2 plants.
c.	traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1.
d.	the traits were lost in the F1 due to blending of the parental traits.
e.	members of the F1 generation had only one allele for each character, but members of the F2 had two alleles for each character.

22.

What are Punnett squares used for?

a.	predicting the result of genetic crosses between organisms of known genotypes
b.	determining the DNA sequence of a given gene
c.	identifying the gene locus where allelic variations are possible
d.	testing for the presence of the recessive allele
e.	more than one of the above

23.

Which of the following is false, regarding the law of segregation?

a.	It states that each of two alleles for a given trait segregate into different gametes.
b.	It can be explained by the segregation of homologous chromosomes during meiosis.
c.	It can account for the 3:1 ratio seen in the F2 generation of Mendel’s crosses.
d.	It can be used to predict the likelihood of transmission of certain genetic diseases within families.
e.	It is a method that can be used to determine the number of chromosomes in a plant.

24.

The fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment means that

a.	none of the traits obeyed the law of segregation.
b.	the diploid number of chromosomes in the pea plants was 7.
c.	all of the genes controlling the traits were located on the same chromosome.
d.	all of the genes controlling the traits behaved as if they were on different chromosomes.
e.	the formation of gametes in plants occurs by mitosis only.

25.

Black fur in mice (B) is dominant to brown fur (b) Short tails (T) are dominant to long tails (t). What fraction of the progeny of the cross BbTt BBtt will have black fur and long tails?

a.	1/16
b.	3/16
c.	3/8
d.	1/2
e.	9/16

26.

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?

a.	1/2
b.	1/4
c.	0
d.	1
e.	1/6

27.

A couple has three children, all of whom have brown eyes and blond 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?

a.	1/16
b.	1/8
c.	1/4
d.	1/2
e.	1

28.

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. If 1,000 F2 offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers? (Assume independent assortment).

a.	65
b.	190
c.	250
d.	565
e.	750

29.

In a cross AaBbCc AaBbCc, what is the probability of producing the genotype AABBCC?

a.	1/4
b.	1/8
c.	1/16
d.	1/32
e.	1/64

30.

Given the parents AABBCc AabbCc, assume simple dominance and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent?

a.	1/4
b.	1/8
c.	3/4
d.	3/8
e.	1

31.

A 1:2:1 phenotypic ratio in the F2 generation of a monohybrid cross is a sign of

a.	complete dominance.
b.	multiple alleles.
c.	incomplete dominance.
d.	polygenic inheritance.
e.	pleiotropy.

Refer to the result below to answer the following questions.

A tall plant is crossed with a short plant, and the progeny are all intermediate in size between the two parental plants.

32.

This could be an example of

a.	incomplete dominance.
b.	polygenic inheritance.
c.	complete dominance.
d.	A and B
e.	B and C

33.

If the intermediate F1 progeny were allowed to self-pollinate, and the F2 progeny were also intermediate in size, but following a normal distribution, this would suggest

a.	incomplete dominance.
b.	polygenic inheritance.
c.	complete dominance.
d.	a strong environmental influence.
e.	codominance.

34.

If the intermediate F1 progeny were allowed to self-pollinate, and 25% of the F2 progeny were tall, 50% were intermediate in size, and 25% were short, this would suggest

a.	incomplete dominance.
b.	polygenic inheritance.
c.	complete dominance.
d.	pleiotropy.
e.	multifactorial inheritance.

35.

In snapdragons, heterozygotes have pink flowers, whereas homozygotes have red or white flowers. When plants with red flowers are crossed with plants with white flowers, what proportion of the offspring will have pink flowers?

a.	0%
b.	25%
c.	50%
d.	75%
e.	100%

36.

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?

a.	ttRr-dwarf and pink
b.	ttrr-dwarf and white
c.	TtRr-tall and red
d.	TtRr-tall and pink
e.	TTRR-tall and red

37.

Skin color in a fish is inherited via a single gene with four different alleles. How many different types of gametes would be possible in this system?

a.	1
b.	2
c.	4
d.	8
e.	16

38.

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?

a.	red white
b.	roan roan
c.	white roan
d.	red roan
e.	The answer cannot be determined from the information provided.

39.

The relationship between genes S and N is an example of

a.	incomplete dominance.
b.	epistasis.
c.	complete dominance.
d.	pleiotropy.
e.	codominance.

40.

A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce

a.	all sharp-spined progeny.
b.	50% sharp-spined, 50% dull-spined progeny.
c.	25% sharp-spined, 50% dull-spined, 25% spineless progeny
d.	all spineless progeny
e.	It is impossible to determine the phenotypes of the progeny.

41.

If doubly heterozygous SsNn cactuses were allowed to self-pollinate, the F2 would segregate in which of the following ratios?

a.	3 sharp-spined : 1 spineless
b.	1 sharp-spined : 2 dull-spined : 1 spineless
c.	1 sharp spined : 1 dull-spined : 1 spineless
d.	1 sharp-spined : 1 dull-spined
e.	9 sharp-spined : 3 dull-spined : 4 spineless

Use the information below to answer the following questions.

Feather color in budgies is determined by two different genes Y and B. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white.

42.

A blue budgie is crossed with a white budgie. Which of the following results is not possible?

a.	green offspring
b.	yellow offspring
c.	blue offspring
d.	A and B
e.	A, B, and C

43.

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?

a.	yyBB and yyBB
b.	yyBB and yyBb
c.	yyBb and yyBb
d.	yyBB and yybb
e.	yyBb and yybb

44.

Three babies were mixed up in a hospital. After consideration of the data below, which of the following represent the correct baby and parent combinations?

Couple # Blood Groups	I A and A	II A and B	III B and O
Baby # Blood Groups	1 B	2 O	3 AB

a.	I-3, II-1, III-2
b.	I-1, II-3, III-2
c.	I-2, II-3, III-1
d.	I-2, II-1, III-3
e.	I-3, II-2, III-1

Use the following information to answer the questions below.

A woman who has blood type A, has a daughter who is type O positive and a son who is type B negative. Rh positive is a simple dominant trait over Rh negative.

45.

Which of the following is a possible genotype for the son?

a.	IBIB
b.	IBIA
c.	ii
d.	IBi
e.	IAIA

46.

Which of the following is a possible genotype for the mother?

a.	IAIA
b.	IBIB
c.	ii
d.	IAi
e.	IAIB

47.

Which of the following is a possible phenotype for the father?

a.	A
b.	O
c.	B
d.	AB
e.	impossible to determine

48.

Which of the following is the probable genotype for the mother?

a.	IAIARR
b.	IAIARr
c.	IAirr
d.	IAiRr
e.	IAiRR

49.

Which of the following is a possible phenotype of the father?

a.	A negative
b.	O negative
c.	B positive
d.	A positive
e.	O positive

50.

What is the chromosomal system for determining sex in mammals?

a.	A
b.	B
c.	C
d.	D
e.	E

51.

What is the chromosomal system for sex determination in grasshoppers and certain other insects?

a.	A
b.	B
c.	C
d.	D
e.	E

52.

What is the chromosomal system for sex determination in birds?

a.	A
b.	B
c.	C
d.	D
e.	E

53.

What is the chromosomal system of sex determination in most species of ants and bees?

a.	A
b.	B
c.	C
d.	D
e.	E

Use the terms listed below to answer the following questions. Each term may be used once, more than once, or not at all.

A. incomplete dominance

B. multiple alleles

C. pleiotropy

D. epistasis

54.

the ability of a single gene to have multiple phenotypic effects

a.	A
b.	B
c.	C
d.	D

55.

the ABO blood group system

a.	A
b.	B
c.	C
d.	D

56.

the phenotype of the heterozygote differs from the phenotypes of both homozygotes

a.	A
b.	B
c.	C
d.	D

57.

cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections

a.	A
b.	B
c.	C
d.	D

58.

Which of the following is an example of polygenic inheritance?

a.	pink flowers in snapdragons
b.	the ABO blood groups in humans
c.	Huntington’s disease in humans
d.	white and purple flower color in peas
e.	skin pigmentation in humans

59.

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by

a.	environmental factors such as soil pH.
b.	the allele for blue hydrangea being completely dominant.
c.	the alleles being codominant.
d.	the fact that a mutation has occurred.
e.	acknowledging that multiple alleles are involved.

Use the information below to answer the following questions.

A woman and her spouse both show the normal phenotype for pigmentation, but both had one parent who was an albino. Albinism is an autosomal recessive trait.

60.

What is the probability that their first child will be an albino?

a.	0
b.	1/4
c.	1/2
d.	3/4
e.	1

61.

If their first two children have normal pigmentation, what is the probability that their third child will be an albino?

a.	0
b.	1/4
c.	1/2
d.	3/4
e.	1

62.

Huntington’s disease is caused by a dominant allele. If one of your parents has the disease, what is the probability that you, too, will have the disease?

a.	1
b.	3/4
c.	1/2
d.	1/4
e.	0

63.

A woman has six sons. The chance that her next child will be a daughter is

a.	1.
b.	0.
c.	1/2.
d.	1/6.
e.	5/6.

The pedigree chart below is for a family, some of whose members exhibit the recessive trait, wooly hair. Affected individuals are indicated by an open square or circle. Use the chart to answer the following questions.

64.

What is the genotype of individual B-5?

a.	WW
b.	Ww
c.	ww
d.	WW or ww
e.	ww or Ww

65.

What is the likelihood that the progeny of D-3 and D-4 will have wooly hair?

a.	0%
b.	25%
c.	50%
d.	75%
e.	100%

66.

What is the probability that individual C-1 is Ww?

a.	3/4
b.	1/4
c.	2/4
d.	2/3
e.	1

67.

People with sickle-cell trait

a.	are heterozygous for the sickle-cell allele.
b.	are usually healthy.
c.	have increased resistance to malaria.
d.	produce normal and abnormal hemoglobin.
e.	all of the above

68.

When a disease is said to have a multifactorial basis, it means that

a.	many factors, both genetic and environmental, contribute to the disease.
b.	it is caused by a gene with a large number of alleles.
c.	it affects a large number of people.
d.	it has many different symptoms.
e.	it tends to skip a generation.

69.

Which of the following terms is least related to the others?

a.	pedigree
b.	karyotype
c.	amniocentesis
d.	chorionic villus sampling
e.	epistasis

Use the answers below to answer the following questions. Each answer may be used once, more than once, or not at all.

A. Huntington’s disease

B. Tay-Sachs disease

C. phenylketonuria

D. cystic fibrosis

E. sickle-cell disease

70.

Substitution of the “wrong” amino acid in the hemoglobin protein results in this disorder.

a.	A
b.	B
c.	C
d.	D
e.	E

71.

Individuals with this disorder are unable to metabolize certain lipids, affecting proper brain development. Affected individuals die in early childhood.

a.	A
b.	B
c.	C
d.	D
e.	E

72.

This is caused by a dominant single gene defect and generally does not appear until the individual is 35-45 years of age.

a.	A
b.	B
c.	C
d.	D
e.	E

73.

Effects of this recessive disorder can be completely overcome by regulating the diet of the affected individual.

a.	A
b.	B
c.	C
d.	D
e.	E

74.

This results from a defect in membrane proteins that normally function in chloride ion transport.

a.	A
b.	B
c.	C
d.	D
e.	E

75.

Which of the following techniques involves the preparation of a karyotype?

a.	amniocentesis
b.	chorionic villus sampling
c.	fetoscopy
d.	A and B only
e.	A, B, and C

Media Activity Questions

76.

All the offspring of a cross between a black-eyed MendAlien and an orange-eyed MendAlien have black eyes. This means that the allele for black eyes is ____ the allele for orange eyes.

a.	codominant to
b.	recessive to
c.	more aggressive than
d.	dominant to
e.	better than

77.

What is the expected phenotypic ratio of a cross between two orange-eyed MendAliens?

a.	3 black-eyed:1 orange-eyed
b.	0 black-eyed:1 orange-eyed
c.	1 black-eyed:3 orange-eyed
d.	1 black-eyed:0 orange-eyed
e.	1 black-eyed:1 orange-eyed

78.

Andalusian chickens with the genotype CBCB are black, those with the genotype CBCW are gray. What is the relationship between the CB and the CW alleles?

a.	CB is dominant to CW.
b.	CB is recessive to CW.
c.	CW is dominant to CB.
d.	The relationship is one of incomplete dominance.
e.	CB and CW are codominant.

79.

Black eyes are dominant to orange eyes, and green skin is dominant to white skin. Sam, a MendAlien with black eyes and green skin, has a parent with orange eyes and white skin. Carole is MendAlien with orange eyes and white skin. If Sam and Carole were to mate, the predicted ratio of their offspring would be:

a.	1 black eyes, green skin: 1 black eyes, white skin: 1 orange eyes, green skin: 1 orange eyes, white skin
b.	3 black eyes, green skin: 3 black eyes, white skin: 9 orange eyes, green skin: 1 orange eyes, white skin
c.	1 black eyes, green skin: 3 black eyes, white skin: 3 orange eyes, green skin: 9 orange eyes, white skin
d.	9 black eyes, green skin: 3 black eyes, white skin: 3 orange eyes, green skin: 1 orange eyes, white skin
e.	There is insufficient information to determine Sam’s genotype.

80.

All the offspring of a cross between a red-flowered plant and a white-flowered plant have pink flowers. This means that the allele for red flowers is ____ to the allele for white flowers.

a.	dominant
b.	codominant
c.	pleiotropic
d.	incompletely dominant
e.	recessive

81.

You conduct a dihybrid cross and then testcross the F1 generation. A ____ ratio would make you suspect that the genes are linked.

a.	3:1
b.	1:2:1
c.	1:1:1:1
d.	7:7:1:1
e.	9:3:3:1

82.

The recombination frequency between gene A and gene B is 8.4%, the recombination frequency between gene A and gene C is 6.8%, and the recombination frequency between gene B and gene C is 15.2%. Which is the correct arrangement of these genes?

a.	ABC
b.	ACB
c.	BCA
d.	CAB
e.	CBA

83.

Hypophosphatemia (vitamin D-resistant rickets) is inherited as a X-linked dominant disorder. An unaffected woman mates with a male with hypophosphatemia. What is the expected phenotypic ratio of their offspring?

a.	1 normal daughter: 1 daughter with hypophosphatemia
b.	1 normal daughter : 1 son with hypophosphatemia
c.	1 daughter with hypophosphatemia : 1 normal son
d.	2 normal daughters : 1 normal son : 1 son with hypophosphatemia
e.	3 normal daughters : 1 son with hypophosphatemia

84.

The sex chromosome complements of both normal human and normal MendAlien males is

a.	XO.
b.	XX.
c.	XY.
d.	YY.
e.	YO.

85.

Mutant tetraploid plants

a.	are usually sickly.
b.	are able to interbreed with their parents.
c.	have an odd number of chromosomes.
d.	are unable to breed with a diploid plant.
e.	are unable to self-fertilize.

86.

Chromosomes and genes share all of the following characteristics except that

a.	they are both present in pairs in all diploid cells.
b.	they both undergo segregation during meiosis.
c.	their copy numbers in the cell decrease after meiosis, and increase during fertilization.
d.	they are both copied during the S phase of the cell cycle.
e.	they both pair up with their homologues during prophase of mitosis.

87.

The improvement of microscopy techniques in the late 1800s set the stage for the emergence of modern genetics because

a.	it revealed new and unanticipated features of Mendel’s pea plant varieties.
b.	it allowed biologists to study meiosis and mitosis, revealing the parallels between the behaviors of genes and chromosomes.
c.	it allowed scientists to see the DNA present within chromosomes.
d.	it led to the discovery of mitochondria.
e.	All of the above are true.

88.

When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?

a.	The involved gene was on the X chromosome.
b.	The involved gene was on the Y chromosome.
c.	The involved gene was on an autosome.
d.	Other male-specific factors influence eye color in flies.
e.	Other female-specific factors influence eye color in flies.

89.

Which of the following statements is (are) true?

a.	The closer two genes are on a chromosome, the higher the probability that a crossover will occur between them.
b.	The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 50%.
c.	Two of the traits that Mendel studied-seed color and flower color-are linked on the same chromosome.
d.	Only B and C are correct.
e.	A, B, and C are correct.

90.

How would one explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced?

a.	The two genes are linked.
b.	The two genes are unlinked.
c.	Recombination did not occur in the cell during meiosis.
d.	The testcross was improperly performed.
e.	Both of the characters are controlled by more than one gene.

91.

New combinations of linked genes are due to which of the following?

a.	nondisjunction
b.	crossing over
c.	independent assortment
d.	mixing of sperm and egg
e.	both A and C

92.

What does a frequency of recombination of 50% indicate?

a.	The two genes likely are located on different chromosomes.
b.	All of the offspring have combinations of traits that match one of the two parents.
c.	The genes are located on sex chromosomes.
d.	Abnormal meiosis has occurred.
e.	Independent assortment is hindered.

The following questions refer to the data and figures below.

CROSS I. Purebred lines of wild-type fruit flies (gray body and normal wings) are mated to flies with black bodies and vestigial wings.

F1 offspring all have a normal phenotype.

CROSS II. F1 flies are crossed with flies recessive for both traits (a testcross).

Resulting Offspring	Normal	Percentage
Gray body; normal wings	575	25.1
Black body; vestigial wings	571	24.9
Black body; normal wings	577	25.2
Gray body; vestigial wings	568	24.8

KEY:
A. CROSS I results give evidence supporting the statement.
B. CROSS I results give evidence against the statement.
C. CROSS II results give evidence supporting the statement.
D. CROSS II results give evidence against the statement.
E. Neither CROSS I nor CROSS II results support the statement.

93.

Vestigial wings are a recessive trait.

a.	A
b.	B
c.	C
d.	D
e.	E

94.

The genes for body color and wing shape are linked.

a.	A
b.	B
c.	C
d.	D
e.	E

95.

An F1 cross should produce flies that will fall into a Mendelian 9:3:3:1 ratio.

a.	A
b.	B
c.	C
d.	D
e.	E

96.

There are 25 centimorgans (map units) between the genes for body color and wing shape.

a.	A
b.	B
c.	C
d.	D
e.	E

97.

A 0.1% frequency of recombination is observed

a.	only in sex chromosomes.
b.	only on genetic maps of viral chromosomes.
c.	on unlinked chromosomes.
d.	in any two genes on different chromosomes.
e.	in genes located very close to one another on the same chromosome.

98.

The following is a map of four genes on a chromosome:

Between which two genes would you expect the highest frequency of recombination?

a.	A and W
b.	W and E
c.	E and G
d.	A and E
e.	A and G

99.

The reason that linked genes are inherited together is that

a.	they are located on the same chromosome.
b.	the number of genes in a cell is greater than the number of chromosomes.
c.	chromosomes are unbreakable.
d.	alleles are paired.
e.	genes align that way during metaphase I.

100.

What is the mechanism for the production of genetic recombinants?

a.	X inactivation
b.	methylation of cytosine
c.	crossing over and independent assortment
d.	nondisjunction
e.	deletions and duplications during meiosis

101.

There is good evidence for linkage when

a.	two genes occur together in the same gamete.
b.	a gene is associated with a specific phenotype.
c.	two genes work together to control a specific characteristic.
d.	genes do not segregate independently during meiosis.
e.	two characteristics are caused by a single gene.

Refer to the figure below to answer the following questions.

102.

In a series of mapping experiments, the recombination frequencies for four different linked genes of Drosophila were determined as shown in the figure. What is the order of these genes on a chromosome map?

a.	rb-cn-vg-b
b.	vg-b-rb-cn
c.	cn-rb-b-vg
d.	b-rb-cn-vg
e.	vg-cn-b-rb

103.

Which of the following two genes are closest on a genetic map of Drosophila?

a.	b and vg
b.	vg and cn
c.	rb and cn
d.	cn and b
e.	b and rb

X, Y, and Z are three genes in Drosophila. The recombination frequencies for two of the three genes are shown below.

104.

Genes X and Y could be

a.	located on different chromosomes.
b.	located very near to each other on the same chromosome.
c.	located far from each other on the same chromosome.
d.	both A and B
e.	both A and C

105.

If the recombination frequency for Y and Z was found to be 50%, this would mean that

a.	genes X and Y are on the same chromosome.
b.	genes X and Y are on different chromosomes.
c.	genes Y and Z are on different chromosomes.
d.	both A and C.
e.	both B and C

106.

Which of the following is true regarding linkage maps? They

a.	always have a total of 100 map units.
b.	can be used to pinpoint the precise physical position of a gene on a chromosome.
c.	are a genetic map based on recombination frequencies.
d.	require preparation of karyotypes.
e.	reflect the frequency of crossing over between X and Y chromosomes.

107.

The frequency of crossing over between any two linked genes is

a.	higher if they are recessive.
b.	different between males and females.
c.	determined by their relative dominance.
d.	the same as if they were not linked.
e.	proportional to the distance between them.

108.

Sturtevant provided genetic evidence for the existence of four pairs of chromosomes in Drosophila by showing that

a.	there are four major functional classes of genes in Drosophila.
b.	Drosophila genes cluster into four distinct groups of linked genes.
c.	the overall number of genes in Drosophila is a multiple of four.
d.	the entire Drosophila genome has approximately 400 map units.
e.	Drosophila genes have, on average, four different alleles.

109.

Map units on a linkage map cannot be relied upon to calculate physical distances on a chromosome because

a.	the frequency of crossing over varies along the length of the chromosome.
b.	the relationship between recombination frequency and map units is different in every individual.
c.	physical distances between genes change during the course of the cell cycle.
d.	the gene order on the chromosomes is slightly different in every individual.
e.	all of the above

110.

A map of a chromosome that includes the positions of genes relative to visible chromosomal features, such as stained bands, is called a

a.	linkage map.
b.	physical map.
c.	recombination map.
d.	cytogenetic map.
e.	banded map.

111.

Males are more often affected by sex-linked traits than females because

a.	males are hemizygous for the X chromosome.
b.	male hormones such as testosterone often exacerbate the effects of mutations on the X chromosome.
c.	female hormones such as estrogen often compensate for the effects of mutations on the X.
d.	X chromosomes in males generally have more mutations than X chromosomes in females.
e.	mutations on the Y chromosome often exacerbate the effects of X-linked mutations.

112.

SRY is

a.	a gene present on the Y chromosome that triggers male development.
b.	a gene present on the X chromosome that triggers female development.
c.	an autosomal gene that is required for the expression of genes on the Y chromosome.
d.	an autosomal gene that is required for the expression of genes on the X chromosome.
e.	required for development, and males or females lacking the gene do not survive past early childhood.

113.

In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?

a.	tortoiseshell female; tortoiseshell male
b.	black female; orange male
c.	orange female; orange male
d.	tortoiseshell female; black male
e.	orange female; black male

114.

Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?

a.	XcXc and XcY
b.	XcXc and XCY
c.	XCXC and XcY
d.	XCXC and XCY
e.	XCXc and XCY

115.

In the following list, which term is least related to the others?

a.	Duchenne muscular dystrophy
b.	autosome
c.	sex-linked genes
d.	color blindness
e.	hemophilia

116.

Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes?

a.	0%
b.	25%
c.	50%
d.	75%
e.	100%

117.

Most calico cats are female because

a.	a male inherits only one of the two X-linked genes controlling hair color.
b.	the males die during embryonic development.
c.	the Y chromosome has a gene blocking orange coloration.
d.	only females can have Barr bodies.
e.	multiple crossovers on the Y chromosome prevent orange pigment production.

118.

A recessive allele on the X chromosome is responsible for red-green color blindness in humans. A woman with normal vision whose father is color-blind marries a color-blind male. What is the probability that a son of this couple will be color-blind?

a.	0
b.	1/4
c.	1/2
d.	3/4
e.	1

119.

In birds, sex is determined by a ZW chromosome scheme. Males are ZZ and females are ZW. A lethal recessive allele that causes death of the embryo is sometimes present on the Z chromosome in pigeons. What would be the sex ratio in the offspring of a cross between a male that is heterozygous for the lethal allele and a normal female?

a.	2:1 male to female
b.	1:2 male to female
c.	1:1 male to female
d.	4:3 male to female
e.	3:1 male to female

120.

A man who carries an X-linked allele will pass it on to

a.	all of his daughters.
b.	half of his daughters.
c.	all of his sons.
d.	half of his sons.
e.	all of his children.

Refer to the information below to answer the following questions.

An achondroplastic male dwarf with normal vision marries a color-blind woman of normal height. The man’s father was six-feet tall, and both the woman’s parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive.

121.

How many of their daughters might be expected to be color-blind dwarfs?

a.	all
b.	none
c.	half
d.	one out of four
e.	three out of four

122.

How many of their sons would be color-blind and of normal height?

a.	all
b.	none
c.	half
d.	one out of four
e.	three out of four

123.

They have a daughter who is a dwarf with normal color vision. What is the probability that she is heterozygous for both genes?

a.	0
b.	0.25
c.	0.50
d.	0.75
e.	1.00

124.

Male calico cats could be the result of

a.	sex-linked inheritance.
b.	nondisjunction, leading to the male calico having two X chromosomes.
c.	incomplete dominance of multiple alleles.
d.	recessive alleles retaining their fundamental natures even when expressed.
e.	a reciprocal translocation.

125.

A Barr body is normally found in the nucleus of which kind of human cell?

a.	unfertilized egg cells only
b.	sperm cells only
c.	somatic cells of a female only
d.	somatic cells of a male only
e.	both male and female somatic cells

126.

Which of these syndromes afflicts mostly males?

a.	Turner syndrome
b.	Down syndrome
c.	Duchenne muscular dystrophy
d.	cri du chat syndrome
e.	chronic myelogenous leukemia

127.

If a human interphase nucleus of a person contains three Barr bodies, it can be assumed that the person

a.	has hemophilia.
b.	is a male.
c.	has four X chromosomes.
d.	has Turner syndrome.
e.	has Down syndrome.

128.

If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis?

a.	All the gametes will be diploid.
b.	Two gametes will be n + 1, and two will be n – 1.
c.	One gamete will be n + 1, one will be n – 1, and two will be n.
d.	There will be three extra gametes.
e.	Two of the four gametes will be haploid, and two will be diploid.

129.

The figure below represents the stained nucleus from a cheek epithelial cell of an individual whose genotype would probably be

a.	XX.
b.	XY.
c.	XYY.
d.	XXX.
e.	XXY.

130.

If a pair of homologous chromosomes fails to separate during anaphase of meiosis I, what will be the chromosome number of the four resulting gametes with respect to the normal haploid number (n)?

a.	n + 1; n + 1; n – 1; n – 1
b.	n + 1; n – 1; n; n
c.	n + 1; n – 1; n – 1; n – 1
d.	n + 1; n + 1; n; n
e.	n – 1; n – 1; n; n

131.

A cell that has 2n + 1 chromosomes is

a.	trisomic.
b.	monosomic.
c.	aneuploid.
d.	polyploid.
e.	both A and C

132.

If a chromosome lacks certain genes, what has most likely occurred?

a.	disjunction
b.	an inversion
c.	a deletion
d.	a translocation
e.	a nonduplication

133.

One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. This is called a (an)

a.	deletion.
b.	disjunction.
c.	inversion.
d.	translocation.
e.	duplication.

134.

In the following list, which term is least related to the others?

a.	trisomic
b.	monosomic
c.	aneuploid
d.	triploid
e.	nondisjunction

135.

A nonreciprocal crossover causes which of the following products?

a.	deletion
b.	duplication
c.	nondisjunction
d.	A and B
e.	B and C

136.

One possible result of chromosomal breakage can be that a fragment reattaches to the original chromosome in a reverse orientation. This is called

a.	disjunction.
b.	translocation.
c.	deletion.
d.	inversion.
e.	aneuploidy.

137.

A human individual is phenotypically female, but her interphase somatic nuclei do not show the presence of Barr bodies. Which of the following statements concerning her is probably true?

a.	She has Klinefelter syndrome.
b.	She has an extra X chromosome.
c.	She has Turner syndrome.
d.	She has the normal number of sex chromosomes.
e.	She has two Y chromosomes.

138.

The karyotype shown below is associated with which of the following genetic disorders?

a.	Turner syndrome
b.	Down syndrome
c.	Klinefelter syndrome
d.	hemophilia
e.	male-pattern baldness

139.

In humans, male-pattern baldness is controlled by a gene that occurs in two allelic forms. Allele Hn determines nonbaldness, and allele Hb determines pattern baldness. In males, because of the presence of testosterone, allele Hb is dominant over Hn. If a man and woman both with genotype HnHb have a son, what is the chance that he will eventually be bald?

a.	0%
b.	25%
c.	33%
d.	50%
e.	75%

140.

Of the following human trisomies, the one that generally has the most severe impact on the health of the individual is

a.	trisomy 21.
b.	Klinefelter syndrome (XXY).
c.	trisomy X.
d.	XYY.
e.	All of the above have equal impact.

141.

What do all human males inherit from their mother?

a.	mitochondrial DNA
b.	an X chromosome
c.	the SRY gene
d.	A and B only
e.	A, B, and C

142.

Which of the following statements is true regarding genomic imprinting?

a.	It explains cases in which the gender of the parent from whom an allele is inherited affects the expression of that allele.
b.	It is greatest in females because of the larger maternal contribution of cytoplasm.
c.	It may explain the transmission of Duchenne muscular dystrophy.
d.	It involves an irreversible alteration in the DNA sequence of imprinted genes.
e.	All of the above are correct.

143.

The pedigree in the figure below shows the transmission of a trait in a particular family. Based on this pattern of transmission, the trait is most likely

a.	mitochondrial.
b.	autosomal recessive.
c.	sex-linked dominant.
d.	sex-linked recessive.
e.	autosomal dominant.

144.

Which of the following statements about mitochondria is false?

a.	Because of the role of the mitochondria in producing cellular energy, mitochondrial diseases often affect the muscles and nervous system.
b.	Because mitochondria are present in the cytoplasm, mitochondrial diseases are transmitted maternally.
c.	Like nuclear genes, mitochondrial genes usually follow Mendelian patterns of inheritance.
d.	Mitochondria contain circular DNA molecules that code for proteins and RNAs.
e.	Many mitochondrial genes encode proteins that play roles in the electron transport chain and ATP synthesis.

Short Answer

Self-Quiz Questions

145.

A man with hemophilia (a recessive, sex-linked condition. has a daughter of normal phenotype) She marries a man who is normal for the trait. What is the probability that a daughter of this mating will be a hemophiliac? That a son will be a hemophiliac? If the couple has four sons, what is the probability that all four will be born with hemophilia?

146.

Pseudohypertrophic muscular dystrophy is an inherited disorder that causes gradual deterioration of the muscles. It is seen almost exclusively in boys born to apparently normal parents and usually results in death in the early teens. Is this disorder caused by a dominant or a recessive allele? Is its inheritance sex-linked or autosomal? How do you know? Explain why this disorder is almost never seen in girls.

147.

Red-green color blindness is caused by a sex-linked recessive allele. A color-blind man marries a woman with normal vision whose father was color-blind. What is the probability that they will have a color-blind daughter? What is the probability that their first son will be color-blind? (Note: The two questions are worded a bit differently).

148.

A wild-type fruit fly (heterozygous for gray body color and normal wings) is mated with a black fly with vestigial wings. The offspring have the following phenotypic distribution: wild type, 778; black-vestigial, 785; black-normal, 158; gray-vestigial, 162. What is the recombination frequency between these genes for body color and wing size?

149.

In another cross, a wild-type fruit fly (heterozygous for gray body color and red eyes) is mated with a black fruit fly with purple eyes. The offspring are as follows: wild type, 721; black-purple, 751; gray-purple, 49; black-red, 45. What is the recombination frequency between these genes for body color and eye color? Using information from problem 4, what fruit flies (genotypes and phenotypes) would you mate to determine the sequence of the body-color, wing-size, and eye-color genes on the chromosome?

150.

What pattern of inheritance would lead a geneticist to suspect that an inherited disorder of cell metabolism is due to a defective mitochondrial gene?

151.

Women born with an extra X chromosome (XXX) are healthy and phenotypically indistinguishable from normal XX women. What is a likely explanation for this finding? How could you test this explanation?

152.

Determine the sequence of genes along a chromosome based on the following recombination frequencies: A-B, 8 map units; A-C, 28 map units; A-D, 25 map units; B-C, 20 map units; B-D, 33 map units.

153.

Assume that genes A and B are linked and are 50 map units apart. An animal heterozygous at both loci is crossed with one that is homozygous recessive at both loci. What percentage of the offspring will show phenotypes resulting from crossovers? If you did not know that genes A and B were linked, how would you interpret the results of this cross?

154.

A space probe discovers a planet inhabited by creatures who reproduce with the same hereditary patterns seen in humans. Three phenotypic characters are height (T = tall, t = dwarf), head appendages (A = antennae, a = no antennae), and nose morphology (S = upturned snout, s = downturned snout). Since the creatures are not “intelligent,” Earth scientists are able to do some controlled breeding experiments, using various heterozygotes in testcrosses. For tall heterozygotes with antennae, the offspring are: tall-antennae, 46; dwarf-antennae, 7; dwarf-no antennae, 42; tall-no antennae, 5. For heterozygotes with antennae and an upturned snout, the offspring are: antennae-upturned snout, 47; antennae-downturned snout, 2; no antennae-downturned snout, 48; no antennae-upturned snout, 3. Calculate the recombination frequencies for both experiments.

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