Midterm Flashcards
1
Q
Genetics is the study of _____.
A
Inherited traits
2
Q
Humans have _____ pairs of chromosomes.
A
23
3
Q
A change in a gene’s DNA sequence is a _____.
A
Mutation
4
Q
A chart that displays paired chromosomes in order of size is a ______.
A
Karyotype
5
Q
The Y chromosome ______.
A
Is a sex chromosome
6
Q
A human body has about ______ cells.
A
30 trillion
7
Q
Shawn’s mother and Heather’s mother are sisters. Shawn and Heather have _____ of their genes in common.
A
1/8
8
Q
Body weight must be a complex trait because ______.
A
It is inherited to an extent, but can be altered by diet and/or exercise
9
Q
Identifying individual drug reactions based on genetics is a growing field called _____.
A
Pharmacogenetics
10
Q
Select the example of genetics.
A
Studying how a disease gene is transmitted within a royal family
11
Q
Sickle-cell anemia results from a beta-globin protein containing the amino acid valine in the place of the amino acid glutamic acid. This is an example of a _____ causing a disease.
A
Mutation
12
Q
Select the example of traditional breeding.
A
Mating dogs with other dogs based on traits such as size, fur color, and temperament
13
Q
Select the true statement regarding types of cells.
A
Somatic cells are diploid, meaning that they have two copies of the human genome
14
Q
Which of the following acts as a quality control center for cells?
A
Endoplasmic reticulum
15
Q
The organelle that is the equivalent of a cellular garbage disposal system is the _____.
A
Lysosome
16
Q
At the point in the cell cycle when mitosis begins _____.
A
Each chromosome consists of two identical chromatids joined at the centromere
17
Q
The two major stages of the cell cycle are _____.
A
Interphase and mitosis
18
Q
The order of events in the cell cycle is _____.
A
G1 to S to G2 to mitosis
19
Q
Chromosomes coil tightly around chromosomal proteins and condense during _____.
A
Prophase
20
Q
During S phase, replicated chromosomes are joined at their _____.
A
Centromeres
21
Q
The part of a chromosome that shortens with each cell division, functioning as a “clock,” is the _____.
A
Telomere
22
Q
Factors that control how often a cell divides include _____.
A
Telomere lengths, hormonal signals, crowding, and growth factors
23
Q
Egg cells are _____.
A
Haploid germ cells
24
Q
The first cell that leads to development of a new individual forms when _____.
A
A sperm and an ovum join
25
Sperm cells and egg cells (oocytes) are called _____.
Gametes
26
During the first meiotic division _____.
Homologous chromosome pairs separate
27
Meiosis is necessary because otherwise _____.
The fertilized ovum will have too much genetic material
28
The correct sequence for the steps of meiosis I is _____.
prophase-metaphase-anaphase-telophase
29
Synapsis occurs during
Prophase I
30
The number of possible chromosome combinations in a human gamete, considering independent assortment but not crossing over, is about _____.
8 million
31
Secondary spermatocytes and secondary oocytes are _____.
Haploid
32
At the end of meiosis, the number of chromosomes in each daughter cell is halved because meiosis has _____.
Two cell divisions after one DNA replication
33
After the second meiotic division, the number of chromosomes in each daughter cell is _____ that of the original parental cell.
Half
34
The number of sperm cells that form from a primary spermatocyte is _____.
4
35
By the end of meiosis I of oogenesis, an oogonium becomes _____.
A secondary oocyte and a polar body
36
Meiosis in females _____.
Is completed only if an oocyte is fertilized
37
After a sperm penetrates the oocyte, the ovum's nuclear membrane disassembles and the two sets of chromosomes approach each other. At this point, the sets of chromosomes are called _____.
Pronuclei
38
Fertilization usually occurs in the _____.
Uterine tube
39
A cell from an organism that has a diploid number of 6 chromosomes has 3 chromosomes lined up in the center of the cell, each chromosome containing two joined sister chromatids. What phase of the cell cycle is this cell in?
Metaphase II of meiosis
40
The difference in mode of inheritance between Huntington disease and cystic fibrosis is that _____.
Huntington disease does not skip generations, but cystic fibrosis can
41
Cystic fibrosis is autosomal recessive. This means that _____.
Both sexes can be affected and can “skip” generations through carriers
42
A person who has two identical alleles for a particular gene is _____ for that gene.
Homozygous
43
Alleles are _____.
Alternate forms of a gene
44
A heterozygote has _____.
Two different alleles for a gene
45
Genotype refers to _____.
The combination of alleles for a particular gene
46
Which of the following represents a monohybrid cross?
Bb x Bb
47
An autosomal dominant trait _____.
Can affect either sex
48
Mode of inheritance reflects _____.
Whether a gene is on an autosome or sex chromosome and whether the allele is recessive or dominant
49
Hillary is 8 years old and has neuronal ceroid lipofuscinosis, also known as Batten disease. It is autosomal recessive. She was fine until age five, when she began to lose her vision and stumble. She had learning difficulties in school and was diagnosed at age six. Hillary may only live into her twenties, experiencing dementia and seizures. Her younger brother Jaden, age six, is healthy, as are her parents. The probability that Jaden is a heterozygote is _____.
2/3
50
Jermaine and Shikia are healthy parents of three young children. The oldest two, Bethany and Amber, are healthy, and they are six and four, respectively. Their youngest child, Roscoe, was born with Peeling Skin Syndrome two years ago. Roscoe's skin constantly peels, and is red and itchy. If Jermaine and Shikia have another child, the probability that he or she will inherit the skin condition is _____.
1/4
51
Sickle cell disease is inherited as an autosomal recessive trait. The genotype of an individual with sickle cell disease is _____.
Homozygous recessive
52
The phenotypic ratio expected from a dihybrid cross is _____.
9:3:3:1
53
Using the product rule, the probability that parents heterozygous for two traits (AaBb) produce an offspring homozygous recessive for the same two traits (aabb) is _____.
1/16
54
Ian and Bryony are both carriers for two autosomal recessive disorders, PKU (chromosome 12) and cystic fibrosis (chromosome 7). They are expecting a daughter. What is the probability that she will have PKU but not CF?
3/16
55
Why is possible to detect the mutation causing Huntington disease at any age?
It is possible to detect the mutation causing Huntington disease at any age because it is a single-gene disorder
56
In a Punnett square where are the gametes listed?
Along to the top and left side of the square
57
For two genes on different chromosomes, the inheritance of one gene does not influence the chance of inheriting the other gene. This is called _____.
The law of independent assortment
58
In humans, a single pair of genes determines an ear lobe characteristic. Free earlobes are dominant and attached lobes are recessive. If one parent has attached lobes and another is heterozygous for free lobes, what is the probability that a child will have free lobes?
One-half
59
The presence of freckles is a dominant characteristic in humans. The absence of freckles is recessive. John and Sarah both have freckles but their daughter does not. What are the genotypes of John and Sarah?
Ff x Ff
60
A couple has three children, two of which have blonde hair. The third child and both parents have dark hair. What can be determined about the gene for hair color in this family?
Blonde hair is autosomal recessive
61
Martha has a widow's peak (dominant trait) and attached earlobes (recessive trait). Martha's dad had a straight hairline and unattached earlobes. What is Martha's genotype?
Wwee
62
Which of the following is not true about blood types?
This is an example of a multiple allele trait and an individual can have up to three different alleles
63
Mendel's results and conclusions were accurate but are seen differently today because we now realize that _____.
Single-gene traits are usually influenced by the environment and other genes
64
Hairlessness in dogs is inherited from a single dominant allele. Inheriting two dominant alleles is lethal for an embryo. Penelope, a hairless dog mates with Arnold, a dog with hair. The probability Penelope will have hairless puppies is _____.
1/2
65
Multiple alleles are common because _____.
A gene sequence can vary in different ways and still encode a functional protein
66
The alleles that control which A, B blood group antigens appear on the surfaces of red blood cells are _____.
Codominant
67
Zuzu is a white cat. She is genotype Ww for the "white masking gene" that reduces the number of melanocytes (pigment-containing cells). As a result, her body makes pigment, but it cannot get into the cells where it would color the fur. Zuzu's white masking gene is _____ to the melanin pigment gene because it prevents full expression of the pigment.
Epistatic
68
In Addam's family, there is an autosomal dominant condition in which webbing attaches the second toe to the third toe and the second toe is longer than the big toe. Only some of the members who have inherited the mutant allele have a second toe longer than the big toe. In addition, the extent of webbing varies. This phenotype is _____.
Variably expressive and incompletely penetrant
69
Epistasis and multiple alleles differ in that _____.
Epistasis is an interaction between two genes, and multiple alleles are variants of the same gene
70
A mitochondrial trait passes from _____.
Mothers to all children
71
A and B are linked genes. In a study of 100 offspring, 94 had parental genotypes for A and B, while 6 were recombinants. A and B are _____ map units apart.
6
72
In meiosis, genes that are found close together on a chromosome ______.
Are usually inherited together
73
Femaleness or maleness is genetically set at _____.
Fertilization
74
Human females are the _____ sex.
Homogametic
75
The pseudoautosomal regions of the Y chromosome correspond to _____.
Counterparts on the X chromosome with which they can cross over
76
A male with a missing SRY gene would be phenotypically a _____.
Female
77
A boy developed signs of sexual maturity at age 3. A possible diagnosis is _____.
Congenital adrenal hyperplasia due to 21-hydroxylase deficiency
78
Homosexuality _____.
Reflects the input of a number of genes and environmental factors
79
The calculation for determining sex ratio is _____.
The number of males divided by the number of females multiplied by 1,000 for people of a particular age
80
X-linked genes have different patterns of expression in females and males because ______.
Males have only one copy of these genes
81
A human male inherits _____.
An X chromosome from his mother and a Y chromosome from his father
82
A daughter can inherit an X-linked recessive disorder if _____.
Her mother is a carrier and her father has the disorder
83
Sixteen-year-old Rhapsody has just learned that her younger brother Clyde is colorblind. Although she knows she has color vision because her cat, Juice, is clearly orange, and she reads that nearly all people with colorblindness are boys, she is concerned about her own sons one day. If she is a carrier for colorblindness, then the risk that a son of hers is colorblind is _____.
1/2
84
X-linked dominant traits are typically expressed _____.
Much more severely in males because they have only one X chromosome
85
The probability that the daughter of a woman with a dominant disease-causing allele on one X chromosome and a normal male will be affected with the disorder is _____.
1/2
86
In males, genes on the X chromosome are _____.
Expressed
87
A gene that determines the heaviness of a man's beard is _____.
Sex-limited
88
In cattle, mahogany spots are dominant in males and recessive in females. This trait is _____.
Sex-influenced
89
Polygenic traits are _____.
Determined by more than one gene
90
Traits that have both inherited and environmental causes are termed _____.
Complex
91
The distinction between complex and polygenic traits is that _____.
Polygenic traits are caused by more than one gene, and complex traits are caused by one or more genes as well as environmental influences
92
In a polygenic trait _____.
Genes contribute to varying degrees, and alleles have differing degrees of impact
93
The pattern of genetic transmission typical of a complex trait is _____.
Continuous variation of phenotypic expression
94
Average height of college students increased throughout the 20th century because _____.
Nutrition improved greatly in that time
95
The number of genes that affect skin, hair, and eye color is _____.
More than 100
96
Heritability refers to _____.
The genetic contribution to the variability of a phenotype in a population at a particular time
97
Heritability of a trait can change because ______.
The environment can change
98
A brother and sister share _____ percent of their genes.
50
99
The proportion of shared genes between a grandparent and grandchild is _____ percent.
25
100
The DNA of dizygotic twins is _____.
As alike as the DNA of any two full siblings
