Allele - An alternate form of a gene for one trait
1. Asexual reproduction - Reproduction that requires only one parent – mitosis only
2. Autosomal______________________________________________________________
______________________________________________________________________
3. Birth defect - an inherited anomaly that affects the functioning of an offspring
4. Chromosome - Long pieces of DNA found in the center (nucleus) of eukaryotic cells
5. Co-dominance____________________________________________________________
______________________________________________________________________
6. Cross _________________________________________________________________
7. Crossing over ___________________________________________________________
______________________________________________________________________
8. Dihybrid - identically heterozygous at two loci for example: RrYy
9. Diploid - A set of chromosomes containing both members of each chromosome pair
10. Dominant - a trait that is observed even if only one allele is present
11. Egg - A female gamete with one copy of each chromosome
12. Embryo - Early stages of growth and differentiation characterized by rapid cell division and the
formation of organ systems
13. Enzyme________________________________________________________________
14. Fertilization - A male and female gamete fuses
15. Gamete________________________________________________________________
16. Gene - A segment of DNA that codes for a particular trait
17. Genetic variation _________________________________________________________
______________________________________________________________________
18. Genome ________________________________________________________________
19. Genotype - genetic makeup of an organism
20. Haploid - A set of chromosomes containing only one member of each chromosome pair
21. Heredity_______________________________________________________________
22. Heterozygous - organisms that have different alleles for a particular trait
23. Homozygous organisms that have identical alleles for a particular trait
Genetics – Heredity Unit Overview KEY
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_____________
24. Homologous_____________________________________________________________
______________________________________________________________________
25. Hybrid_________________________________________________________________
______________________________________________________________________
26. Incomplete dominance_____________________________________________________
______________________________________________________________________
27. Meiosis________________________________________________________________
28. Mitosis________________________________________________________________
29. Monohybrid_____________________________________________________________
30. Multicellular organism______________________________________________________
31. Non-disjunction__________________________________________________________
______________________________________________________________________
32. Ovule__________________________________________________________________
33. Offspring_______________________________________________________________
34. Pedigree________________________________________________________________
35. Phenotype - physical appearance of an organism _____________
36. Probability______________________________________________________________
37. Punnett Square __________________________________________________________
38. Recessive - a trait that requires both alleles to be observed _____________
39. Recombinant ____________________________________________________________
______________________________________________________________________
40. Replication _____________________________________________________________
41. Segregation_____________________________________________________________
42. Sexual reproduction - Reproduction that requires two parents
43. Sex-linked______________________________________________________________
______________________________________________________________________
44. Somatic cell_____________________________________________________________
45. Sperm - A male gamete with one copy of each chromosome ___________
Genetics – Heredity Unit Overview KEY
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46. Trait _________________________________________________________________
47. X chromosome ___________________________________________________________
48. Y chromosome ___________________________________________________________
49. Zygote ________________________________________________________________
50. Hemophilic _____________________________________________________________
51. Inheritance _____________________________________________________________
52. Mendel ________________________________________________________________
Diagram and label each stages of mitosis prior to cytokinesis
Diagram and label each stages of meiosis
Genetics – Heredity Unit Overview KEY
3
Genetics Unit Study Guide – Heredity
KEY
1.
One step in a single eukaryotic cell becoming two daughter cells is the process of mitosis.
2.
The principle that describes that genes segregate without influence on each others
inheritance: Independent assortment
3.
If an organism has a gamete containing 12 chromosomes, one would expect each of its body
cells to contain 24 chromosomes.
4.
Compared to the number of chromosomes contained in a body cell of a parent, how many
chromosomes would normally be contained in a gamete?1/2, one-half as many
5.
The numbers in the figure represent the chromosome number
found in each of the dog cells shown. The processes that are
occurring at A and B are A=Meiosis and B=fertilization.
6.
Which chromosomes shown in the picture above are homologous to each other? A and C
7.
During the formation of gametes, independent assortment occurs between homologous
chromosomes
8.
Mendel’s hypothesis that two factors for each trait are segregated during the formation of
gametes is explained by separation of homologous chromosomes during meiosis.
9.
If a corn plant has a genotype of Ttyy, what are the possible genetic combinations that could
be present in a gamete (single grain of pollen) from this plant? Ty or ty
10.
The law of independent assortment states that
independently of each other.
11.
The law of segregation states that alleles of a gene separate from each other during
meiosis.
12.
To describe how traits can disappear and reappear in a certain pattern from generation to
generation, Mendel proposed the Law of Independent Assortment.
Genetics – Heredity Unit Overview KEY
4
gene pairs sort randomly and
13.
One of the plants that the scientist is studying has an extra copy of one chromosome in all its
cells. This variation most likely occurred during Meiosis
14.
Crossing-over most commonly results in new combinations of genes
BR
Br
bR
Br
BR
BBRR
BBRr
BbRR
BbRr
Br
BBRr
BBrr
BbRr
Bbrr
bR
BbRR
BbRr
X
Br
BbRr
Y
A male guinea pig with black, rough hair (BbRr) was crossed with a female guinea pig with black,
rough hair (BbRr). The Punnett square contains the partial results from this mating. (B=black,
b=white, R=rough, r=smooth)
15.
According to the figure above, what is the genotype for X? bbRR and for Y? BBrr
16.
Using the diagram above, explain the pattern of inheritance for hemophilia (a blood disease)
trait. The allele for hemophilia is carried on the X chromosome.
17.
Above is a pedigree for the recessive trait, attached ears (aa). The dominant trait is
unattached ears (A). The black circles indicate people who have the recessive trait.
Using the chart, what would be the genotype of person I,2? Aa
Using the chart, what would be the genotype of person II,2? Aa
Genetics – Heredity Unit Overview KEY
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XH
Xh
h = hemophiliac
Xh
XHXh
XhXh
H = normal
Y
XHY
4
18.
Using the chart above, how many offspring will be hemophiliacs? 2/4
19.
The phenotype of box 4 is XhY = hemophiliac male
20.
In fruit flies, the gene for red eyes (R) is dominant and the gene for sepia eyes (r) is recessive. What are the possible
combinations of genes in the offspring of two red-eyed heterozygous flies (Rr)?
Rr x Rr
R
r
R
RR
Rr
r
Rr
rr
1/4 RR, 2/4 Rr, 1/4 rr
21.
The appearance of an organism is its phenotype
22.
To determine the genotype of an individual that shows the dominant phenotype, you would cross
that individual with one that is homozygous recessive
23.
In a two-factor cross between an individual with the genotype RRYY and an individual with the
genotype rryy, all of the offspring will have the genotype RrYy
24.
A segment of DNA that controls a particular hereditary trait is called a gene
25.
The genetic makeup of an organism is called its genotype
26.
Having two similar, dominant alleles for a trait is called homozygous dominant
27.
A cross between two plants that have pink flowers produced plants that have red, pink, or
white flowers. What is the most likely explanation for these results? Inheritance involving
incomplete dominance.
28.
An organism in which two alleles for a trait are different is heterozygous
29.
The phenotype of an organism is the appearance of an organism reflecting all the traits
that are actually expressed.
30.
Tallness (T) is dominant to shortness (t) in pea plants. What is the genotype of a pea plant
that is heterozygous for tallness? Tt
31.
An individual heterozygous (Tt) for a trait and an individual homozygous recessive (tt) for the
trait are crossed and produce offspring that are of two different phenotypes.
Tt x tt
t
t
Genetics – Heredity Unit Overview KEY
T
Tt
Tt
t
tt
tt
6
32.
A scientist crossed a tall pea plant with a short pea plant. All of the four hundred offspring
produced were tall pea plants. Explain these results. TT x tt indicating that the allele for
tall plants is dominant.
33.
A family has eight children. Six children have second toes that are longer than the big toe.
Two children have second toes that are shorter than the big toe. What are the most likely
genotypes of the parents? Ratio of 3 long to 1 short indicates typical phenotypic ratios
that result from two heterozygous parents: Ll and Ll
34.
A homozygous individual would have what possible genotype? Two dominant alleles or Two
recessive alleles.
35.
If two parents with dominant phenotypes produce an offspring with a recessive phenotype,
what can you say about the parents? The parents were both heterozygous
36.
In a monohybrid cross between two heterozygous parents, one would expect the offspring to
be 1 DD: 2 Dd : 1dd
37.
Living things grow because organisms produce more and more cells by mitosis.
38.
How are mature human sperm and eggs similar? They have the same number of chromosomes
in the nuclei.
39.
Female gametes are called eggs.
40.
Each egg and sperm cell contains a haploid number of chromosomes. After fertilization, a
zygote is formed have a diploid number of chromosomes.
41.
How many chromosomes are there in a human gamete? 23
42.
A human zygote contains 46 chromosomes, fifty percent of the total coming from each parent
cell.
43.
Sex cells are also called gametes
44.
A fertilized egg is also called a(n) zygote
45.
Which diagram correctly illustrates the fusion of normal gametes that will most likely produce
a human male? Picture 4 showing a male sperm and a female egg.
Genetics – Heredity Unit Overview KEY
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46.
A developing heart increases in size through the process of Mitosis
47.
A man with a certain syndrome marries a woman who is normal for that trait. They have 6
children, three girls and three boys. All four the girls have the same syndrome as the father
whereas none of the boys is affected. Which type of heredity is not possible here? Y-linked
48.
Nondisjunction is related to a number of serious human disorders. How does nondisjunction
cause these disorders? Alters the chromome number
49.
What occurs during the process of meiosis in humans that can lead to a child with the condition
of Down Syndrome? Production of gametes with one duplicate chromosome. Nondisjunction
of chromosome 21 occurs during meiosis.
50.
What is the name for this process and what causes it? Nondisjuction due to improper
segregation of chromosomes.
51.
A white mouse whose parents are both white produces only brown offspring when mated with a
brown mouse. The white mouse is most probably homozygous recessive.
52.
Given that the dominance hierarchy of rabbit fur color alleles is C>Cch>Ch, from grey to
chinchilla to Himalayan, respectively what would be the percentage of Himalayan colored
rabbits from parents with C Ch and Cch Ch ?
C Ch x Cch Ch
C
Ch
Cch
C Cch
Cch Ch
1/4 CCch, 1/4 CCh, 1/4 CchCh , 1/4 ChCh
Ch
C Ch
Ch Ch
¼ = 25% ChCh = Himalayan colored
53.
The diagram shows a diploid cell with two homologous pairs of
chromosomes. Due to independent assortment, the possible allelic
combinations that could be found in gametes produced by the meiotic
division of this cell are Bd, BD, bd, bD
54.
Using the figure below, which process would result in the formation of chromosome C from
chromosomes A and B? Crossing Over
55. Suppose an animal is heterozygous AaBb, and the traits are not linked. When meiosis occurs, list
out the possible combinations of gametes that can be made for these traits?
4 possible combinations AB, Ab, aB, and ab
56. Suppose an animal is heterozygous AaBbCc, and the traits are not linked. When meiosis occurs,
list out the total possible combinations of gametes that can be made for these traits?
8 possible combinations:
ABC
AbC
aBC
abC
ABc
Abc
aBc
abc
Genetics – Heredity Unit Overview KEY
8
57.
A true-breeding tall pea plant is crossed with a true-breeding short pea plant, and all the
offspring are tall. What is the most likely genotype of the offspring assuming a single-gene
trait?
1) TT x tt = Tt
58.
T
T
t
Tt
Tt
t
Tt
Tt
4/4 Tt
In mice, black is dominant to white color and color is determined by a single gene. Two black
mice are crossed. They produce 2 black offspring and one white offspring. If the white
offspring is crossed with one of its parents, what percent of the offspring are expected to be
white?
1) Parents must be heterozygous if one white is
59.
B
b
produced from two black parents (Bb x Bb)
b
Bb
bb
2/4 bb
2) Bb x bb
b
Bb
bb
50% white
Mendel crossed a true-breeding plant that produced green seeds with a true-breeding plant
that produced yellow seeds to produce an F1 generation. The entire F1 generation produced
yellow seeds. Then he crossed the F1 offspring with each other to produce the F2 generation.
From the F2 generation, he counted 6022 yellow seeds. What is an estimate of the number of
green seeds he collected from the F2 generation?
Yellow is dominant
F2
Y
y
75% Yellow (YY,Yy); 25% Green (yy)
1) YY x yy = Yy (F1)
Y
YY
Yy
(0.75)(x) =6,022; x = 8,030 total seeds
2) Yy x Yy = (F2)
y
Yy
yy
(8,030)(0.25) = 2,008 green seeds estimate
60.
In which situation are the phenotypes of F2 offspring expected to follow the ratio of 9:3:3:1.
A dihybrid cross for two unlinked traits
61.
If two heterozygous individuals are crossed, what percent of their offspring are also expected
to be heterozygous
Hh x Hh
H
h
H = dominant
H
HH
Hh
H = recessive
h
Hh
hh
Genetics – Heredity Unit Overview KEY
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2/4 Hh = 50%
62.
A geneticist crossed fruit flies to determine whether two traits are linked. The geneticist
crossed a fly with blistery wings and spineless bristles (bbss) with a heterozygous fly that had
normal wings and normal bristles (BbSs). Which results in the next generation would suggest
these traits are linked?
If unlinked
wings/bristles
If linked
bs
bs
bs
bs
4BbSs - normal/normal
BS
BbSs
BbSs
BbSs
BbSs
4Bbss - normal/ spineless
Bs
Bbss
Bbss
Bbss
Bbss
4 bbSs - blistery /normal
bS
bbSs
bbSs
bbSs
bbSs
4 bbss – blistery /spineless
bs
bbss
bbss
bbss
bbss
25% of each kind
63.
bs
bs
50% normal/normal
BS
BbSs
BbSs
50% blistery /spineless
bs
bbss
bbss
50% of each kind
Recall that crossing over can occur resulting
in rare instances of other combination
A man heterozygous for blood type A marries a woman heterozygous for blood type B. The
chance that their first child will have type O blood is ____.
To have a type o child
64.
wings/bristles
A
o
Each offspring born will
Parents must be heterozygous
B
BA
Bo
have a 25% change of being oo,
Ao x Bo
o
Ao
oo
with Type O blood
According to figure below, what is the chance that individual A will be afflicted with
Huntington's?
Autosomal
D
d
Circle = female; square = male
½ = 50% chance w/ disease
D = Disease; d = normal
d
Dd
dd
With one child affected dad has
d
Dd
dd
to be a carrier (Dd)
Genetics – Heredity Unit Overview KEY
10
65.
Consider the cell labeled X in the figure below containing 4 chromosomes. Which of the four
cells below it represents a
healthy gamete that could be
produced from this cell?
A because it has a chromosome
from each homologous
chromosome pair
66. What is the best description of the events that take place during anaphase II?
Sister chromatids are separated and pulled to opposite sides of the cell
67. During which phase of meiosis do homologous pairs of chromosomes line up next to one another
along the equator? Metaphase I
Metaphase I is then followed by Anaphase I when homologous chromosomes travel to
opposites sites of the cell reducing the chromosome number from 2n to n
68. Which stage of meiosis is responsible for the law of independent assortment?
Metaphase I
Metaphase
Sister chromatids
Genetics – Heredity Unit Overview KEY
Anaphase
Telophase
centromere
spindle fibers
11
Prophase
centrioles
70. What fraction of this cross will be recessive for both traits? Parent gametes must both be
recessive mx which only occurs in 1 of sixteen possiblilities, so the
fraction is 1/16.
71. If individual III-2 marries a person with the same genotype as individual I-1, what is the chance
that one of their children will be afflicted with hemophilia?
The chance is 0% for children to be
afflicted = exhibit the disease;
However, there is a 50% that one
of their children may be a carrier
(1/2 shaded)
72. What type of inheritance pattern does
the trait represented by the shaded
symbols illustrate? Sex-linked carriers
73. For the trait being followed in the pedigree, individuals II-1 and II-4 can be classified as
carriers.
74. What is the relationship between individual I-1 and individual III-2?
Grandmother (I-1) and Grandson (III-2)
75. The coat color in Labrador retrievers is controlled by two sets of alleles that interact
epistatically. The gene E/e determines whether the fur has pigment or not and is epistatically
dominant to the gene B/b, which controls the darkness of pigment when it is there. A breeder
crosses a purebred black Lab, with the genotype BBEE, and a purebred yellow Lab with the
genotype bbee, producing offspring that are black. A test cross is done between these offspring
and an individual with the genotype bbee. What is the expected ratio of black:chocolate:yellow?
Cross 1) BBEE x bbee = BbEe
BE
Be
bE
be
4/16 = ¼ BbEe = black
BbEe = Black
be
BbEe
Bbee
bbEe
bbee
4/16 = ¼ Bbee = black not dark
Cross 2) BbEe x bbee
be
BbEe
Bbee
bbEe
bbee
4/16 = ¼ bbEe = yellow
be
BbEe
Bbee
bbEe
bbee
4/16 = ¼ bbee = yellow
be
BbEe
Bbee
bbEe
bbee
Note: Bbee = cholate
1 Black: 1 Chocolate: 2 Yellow
76. One step in a single eukaryotic cell becoming two daughter cells is the process of mitosis.
77. How are mature human sperm and eggs similar?
They both have the same number of chromosomes in their nuclei.
Genetics – Heredity Unit Overview KEY
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