Download 4th- 9 Week`s Exam Study Guide 4th Nine Weeks Study Guide 1

4th- 9 Week’s Exam Study Guide
4th Nine Weeks Study Guide
1.During what stage of the cell cycle does replication occur?
2.What are chromatids?
3.What forms around the chromatids during mitosis?
4.In Mendel’s experiments, what proportion of the plants in the F2 generation had a trait that had been absent in the F1
generation?
5.Factors that control traits are called
6.Scientists call an organism that has two different alleles for a trait a
7.What does the notation TT mean to geneticists?
8.What is probability?
9.What does a Punnett square show?
10.If a homozygous black guinea pig (BB) is crossed with a homozygous white guinea pig (bb), what is the
probability that an offspring will have black fur?
11.What is the chromosome theory of inheritance?
12.What happens during meiosis?
13.When sex cells combine to produce offspring, each sex cell will contribute
14.A mutation is harmful to an organism if it
15.Which term refers to physical characteristics that are studied in genetics?
16.The different forms of a gene are called
17.An organism’s genotype is its
18.Chromosomes are made up of
19.Which of these traits is controlled by a gene with multiple alleles?
20.What are multiple alleles?
21.Why does height in humans have such a wide variety of phenotypes?
22.What controls variations in skin color among humans?
23.What factors can affect a person’s height?
24.Why are sex-linked traits more common in males than in females?
25.How does a geneticist use pedigrees?
26.What is a pedigree?
27.What is a karyotype?
28.Cloning results in two organisms that are
29.What is a genome?
30.Both parents of a child have type A blood. What might their child’s blood type be?
31.Sex-linked genes are genes on
32.In an attempt to produce a potato that tastes good and also resists disease, plant breeders crossed a potato variety
that tastes good with a variety that resists disease. This technique is an example of
33.Which form of selective breeding crosses parents with the same or similar sets of alleles?
34.A carrier is a person who has
35.What must occur for a girl to be colorblind?
36.Hemophilia is caused by a(n)
37.Down syndrome most often occurs when
38.What genetic disorder results in abnormally shaped blood cells?
39.Many characteristics are affected by interactions between genes and
40.Adults with Down syndrome can often find work because they have received
Modified True/False
Indicate whether the sentence or statement is true or false. If false, change the identified word or phrase to make the
sentence or statement true.
41.When Mendel crossed purebred short plants with purebred tall plants, all of the offspring were short.
_________________________
42.A hybrid is the offspring of parents that have different alleles for a trait. _________________________
43.A pea plant that is heterozygous for tall stems has the alleles Tt. _________________________
44.A Punnett square shows all the possible combinations of alleles resulting from a cross.
_________________________
45.An organism’s phenotype is its allele combinations. _________________________
46.The sex cells produced by meiosis have twice the number of chromosomes as the parent cells.
_________________________
47.Chromosomes carry genes from parents to offspring. _________________________
48.The number of DNA bases along a gene specifies the type of protein that will be produced.
_________________________
49.A mutation in a sex cell can be passed to offspring. _________________________
50.Even if a gene has multiple alleles, a person cannot have more than three of those alleles.
_________________________
51.Traits that have many different phenotypes, such as height and skin color, are often controlled by a single gene.
_________________________
52.A person’s environment can affect his or her genotype for certain traits, such as height.
_________________________
53.Sex-linked traits that are controlled by recessive alleles are more likely to show up in males.
_________________________
54.A male is represented by a square in a pedigree. _________________________
55.A genetic disorder in which an abnormal form of hemoglobin is produced is hemophilia.
_________________________
56.A doctor can look at the chromosomes of a cell in a karyotype. _________________________
57. The technique called cloning produces an organism that is genetically identical to its parent.
_________________________
58.Except for identical twins, all people have the same DNA. _________________________
59. The goal of DNA fingerprinting is to identify the DNA sequence of every gene.
_________________________
Completion
Complete each sentence or statement.
60. If a(n) ____________________ allele is present, its trait will appear in the organism.
61. A chart used to predict results of genetic crosses is known as a(n) ____________________.
62. In a cross between two hybrid Tt pea plants, ____________________ percent of the offspring will be Tt.
63. An organism that has two dominant or two recessive alleles is said to be ____________________ for that
trait.
64. Genes are carried from parents to their offspring on structures called ____________________.
65. The process in which a parent cell divides twice to produce sex cells is called ____________________.
66. If all of the sex cells of an organism have the T allele, the genotype of that organism must be
____________________.
67. The substitution of one base for another during DNA replication is an example of a(n)
____________________.
68. An organism can be heterozygous for some traits and ____________________ for others.
69. The three alleles on the single gene that controls blood type are said to be ____________________
alleles.
70. When many genes control a trait, the trait will show a large number of ____________________.
71. People who have the genetic disorder called ____________________ suffer from abnormally low levels
of oxygen in the blood.
72. A person who has the genetic disorder called ____________________ bleeds easily.
73. Breeders use a technique called ____________________ to cross genetically different individuals.
74. A selective breeding technique called ____________________ has been used to breed purebred
racehorses.
75. A gene is said to have multiple alleles if it has more than ____________________ alleles.
76. A pattern produced from fragments of the DNA of a specific person is called a(n)
____________________.
Short Answer
Use the diagram to answer each question.
77. Identify the stages of the cell cycle represented by drawings 1–5.
78. Identify structure A and describe its function.
79. Identify the structures labeled B. What do these structures contain?
Use the diagram to answer each question.
80. Which trait—white flowers or purple flowers—is controlled by a dominant allele? Which is controlled by
a recessive allele? How do you know?
81. In which generation are the parents purebred? In which generation are they hybrids?
82. In the F1 generation, what is the genotype of the offspring? What is their phenotype?
83. In the F2 generation, what percent of the offspring have purple flowers? What is the genotype of the
purple-flowered offspring?
Use the diagram to answer each question.
84. Which pairs of individuals in the pedigree have children?
85. Which individuals have the trait that is traced by the pedigree?
86. Which individuals are carriers of the trait that is traced by the pedigree?
Essay
87. In pea plants, green pod color is controlled by a dominant allele. Yellow is controlled by a recessive
allele. Explain why a plant with yellow pods can never be a hybrid.
88. A woman gives birth to a son. Two years later, she gives birth to another son. What is the probability that
her third child will be a girl? Explain your reasoning.
89. Explain the function of meiosis.
90. Contrast the effects of harmful and helpful mutations.
91. Human eyes come in a variety of colors ranging from light blue to very dark brown. Explain why eye
color is not likely to be controlled by a single gene.
92. Is it possible for a son to inherit an allele on an X chromosome from his father? Explain why or why not.
93. Explain what causes cystic fibrosis and describe its effects on the body.
4th Nine Weeks Study Guide- Answers
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interphase
identical strands of chromosomes
two new nuclei
one fourth
genes
hybrid
two dominant alleles
a number that describes how likely it is than an event will occur
all the possible outcomes of a genetic cross
100 percent
genes are carried from parent to offspring
chromosome pairs separate and are distributed into new sex cells
half the number of chromosomes in the body cells
reduces the organism chances for survival and reproduction
traits
alleles m
genetic makeup
one pair of alleles
blood type
three or more forms of a gene that code for a single trait
height is controlled by at least four genes
many genes
both genes and environmental factors
a recessive allele on the x chromosome will always produce the trait in a male
to trace the inheritance of traits in humans
a chart that tracks which members of a family have a particular trait
a picture of the chromosomes in a cell
genetically identical
all the DNA in one cell of an organism
Type A or type O
the x and y chromosomes
hybridization
inbreeding
one recessive and one dominant allele for a trait
each parent must have two codominant alleles for colorblindedness
recessive allele on the x chromosome
chromosomes fail to separate properly during meiosis
sickle cell disease
the environment
education and job training
MODIFIED TRUE/FALSE
41. ANS: F, tall
42.
43.
44.
45.
ANS:
ANS:
ANS:
ANS:
T
T
T
F, genotype
46. ANS: F, half
47. ANS: T
48. ANS: F, order
49. ANS: T
50. ANS: F, two
51. ANS: F, many genes
52. ANS: F, phenotype
53. ANS: T
54. ANS: T
55. ANS: F
sickle-cell disease
sickle cell disease
56. ANS: T
57. ANS: T
58. ANS: F, different
59. ANS: F, the Human Genome Project
COMPLETION
60. ANS: dominant
61. ANS: Punnett square
62. ANS:
50
fifty
63. ANS: homozygous
64. ANS: chromosomes
65. ANS: meiosis
66. ANS: TT
67. ANS: mutation
68. ANS: homozygous
69. ANS: multiple
70. ANS: phenotypes
71. ANS:
sickle-cell disease
sickle cell disease
72. ANS: hemophilia
73. ANS: hybridization
74. ANS: inbreeding
75. ANS:
two
2
76. ANS: DNA fingerprint
SHORT ANSWER
77. ANS:
1 is anaphase. 2 is prophase. 3 is interphase. 4 is telophase. 5 is metaphase.
78. ANS:
A is a centromere, which holds the two chromatids of a chromosome together.
79. ANS:
The structures are chromatids. They contain condensed chromatin.
80. ANS:
White flowers are controlled by a dominant allele. Purple flowers are controlled by a recessive allele.
Dominant alleles are represented by capital letters, and recessive alleles are represented by the lowercase
versions of the same letters.
81. ANS:
The parents in the F1 generation are purebred. The parents in the F2 generation are hybrids.
82. ANS:
The genotype is Ww. The phenotype is white flowers.
83. ANS:
In the F2 generation, 25% of the offspring have purple flowers. Their genotype is ww.
84. ANS:
Pair A and B, pair C and D, pair F and G, and pair H and I have children.
85. ANS:
F and J have the trait.
86. ANS:
A, C, N, and O are carriers of the trait.
ESSAY
87. ANS:
Because the allele for yellow is recessive, plants with yellow pods must have two recessive alleles. A
hybrid would have one dominant allele and one recessive allele, and would therefore be green.
88. ANS:
The probability is 1 in 2, or 50 percent. The two possible results—having a boy or having a girl—are
equally likely with each birth. Because each birth is an independent event, the probability that one result
will occur does not depend on previous births.
89. ANS:
Meiosis ensures that each sex cell gets half the number of chromosomes in a body cell. If meiosis did not
occur, the sperm cell and the egg cell would each have the same number of chromosomes as a body cell.
When the two cells combined, the offspring would have twice the normal number of chromosomes.
90. ANS:
A harmful mutation reduces the organism’s chances for survival and reproduction. A helpful mutation
increases an organism’s chances for survival and reproduction.
91. ANS:
Traits that show a large number of phenotypes are usually controlled by many genes. With multiple genes
and two or more alleles for each gene, there are many possible combinations of alleles and phenotypes.
92. ANS:
It is not possible because males only have one X chromosome, which always comes from the mother.
93. ANS:
Cystic fibrosis is caused by a recessive allele that causes the body to produce abnormally thick mucus in
the lungs and intestines. People with cystic fibrosis have difficulty breathing.