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Your body is composed of a dazzling array of different cell types. Each cell type develops its own unique properties. How does this happen? A. Each cell type is provided with its own specialized set of genes during cell division. |
B. All cells (with very few exceptions) contain the same set of genes, but the process of gene expression determines which genes are active in each cell. |
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Operons are a standard method for gene regulation in _____. A. all organisms |
C. prokaryotes but not eukaryotes |
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Within an operon, repressors _____. A. block gene transcription to RNA by attaching to the operator |
A. block gene transcription to RNA by attaching to the operator |
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To begin the process of gene transcription, RNA polymerase attaches to _____. |
B. the promoter associated with the target gene |
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The lac operon controls expression of three genes that produce lactose-digesting enzymes. What role does lactose play in regulating the lac operon? |
C. It binds to and disables the repressor protein, thereby allowing production of the three enzymes. |
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The initiation of transcription requires that enhancers bind to _____. A. transcription factors |
A. transcription factors |
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Although all of the cells in your body contain a complete set of DNA, different types of cells arise because__________. |
A. different genes are switched on and off in each type of cell |
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The process by which cells become specialized is called _____. A. differentiation |
A. differentiation |
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Gene expression involves the flow of information from genes to proteins, which is accomplished via _____ and _____. A. transcription…translation |
A. transcription…translation |
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In prokaryotes, a group of closely associated genes with related functions is called _____. A. an operon |
A. an operon |
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It is possible for a cell to make proteins that last for months; hemoglobin in red blood cells is a good example. However, many proteins are not this long-lasting. They may be degraded in days or even hours. What is the advantage of short-lived proteins? A. Cells lack the raw materials to make most of the proteins they need. |
C. Short-lived proteins enable the cells to adjust (control) gene expression when this is critical to their well-being. |
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Homeotic genes are best described as __________. A. genes that regulate groups of other genes that determine what body parts will develop in which locations |
A. genes that regulate groups of other genes that determine what body parts will develop in which locations |
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The control of gene expression is more complex in multicellular eukaryotes than in prokaryotes because __________. A.eukaryotic cells are much smaller |
D. in a multicellular eukaryote, different cells are specialized for different functions |
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In eukaryotes, DNA packing seems to affect gene expression primarily by __________. A. controlling access to DNA |
A. controlling access to DNA |
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Alternative RNA splicing refers to __________. A. adding a tail to one end of the messenger RNA |
C. splicing different exons out of the same RNA transcripts |
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Regions of noncoding DNA within a gene are called _____. A. coding sections |
D. introns |
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In addition to gene regulation during transcription, other mechanisms regulate gene expression following transcription, including __________. A. initiation of translation, breakdown of RNA, and protein alteration |
A. initiation of translation, breakdown of RNA, and protein alteration |
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The genes that malfunction and cause a cell to become cancerous usually __________. A. regulate cell division |
A. regulate cell division |
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All your cells contain proto-oncogenes, which can change into cancer-causing genes. Why do cells possess such potential time bombs? A. Cells produce proto-oncogenes as a by-product of mitosis. |
C. Proto-oncogenes are necessary for normal control of cell division. |
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Which of the following would be most likely to lead to cancer? A. mutations in proto-oncogenes and inactivation of a tumor-suppressor gene |
A. mutations in proto-oncogenes and inactivation of a tumor-suppressor gene |
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How can a single RNA transcript be translated into different polypeptides? A. Two different genes can produce the same RNA transcript, which will then be translated differently. |
C. There is more than one way to splice an RNA transcript. |
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A breakthrough in animal cloning in the late 1990s came with the development of nuclear transplantation. Nuclear transplantation is a process whereby __________. A. nuclei from two cells from the same animal are exchanged and implanted into the donor |
C. a nucleus from an adult donor is placed into a cell without a nucleus, put in culture to produce an early embryo, and implanted into a surrogate mother |
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Which of the following cells is least differentiated? A. homeoboxes |
C. embryonic stem cells |
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Which of these is a type of post-transcriptional regulation of gene expression? A. binding of transcription factors to enhancers |
B. alteration of proteins |
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What is the first level of control of eukaryotic gene transcription? A. the binding and unbinding of transcription factors to enhancer sequences |
C. DNA packing and unpacking |
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You have inserted the gene for human growth factor into the E. coli lactose operon, replacing the lactose structural genes with the gene for human growth factor. What substance must you add to your culture of bacteria to cause it to produce human growth factor for you? A. repressor protein |
E. lactose |
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Dioxin, produced as a by-product of some industrial chemical processes, is suspected of causing cancer and birth defects in animals and humans. It apparently acts by entering cells and binding to proteins, consequently altering the pattern of gene expression. In this way, dioxin acts by mimicking the action of __________. A. transcription factors |
A. transcription factors |
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A DNA microarray enables researchers to determine __________. A. which genes are being expressed |
A. which genes are being expressed |
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In frogs, when the nucleus of an intestinal cell of a tadpole is transferred to an egg whose nucleus has been removed (nuclear transplantation), some of the eggs will develop into normal tadpoles. This demonstrates __________. A. that intestinal cells are not differentiated |
C. that differentiated cells have retained all of their genetic potential |
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Using a cell taken from a multicellular organism to grow a genetically identical new organism is called _____. A. transplantation |
E. cloning |
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Why, of all cell types, do embryonic stem cells (ES cells) have the greatest potential for use in the treatment of disease? A. They are undifferentiated cells that have the potential to differentiate into all of the different specialized cells of the body. |
A. They are undifferentiated cells that have the potential to differentiate into all of the different specialized cells of the body. |
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Which of the following statements is true of colon cancer? A. Colon cancer usually results from a series of mutations. |
A. Colon cancer usually results from a series of mutations. |
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What is a proto-oncogene? A. It is a type of gene found only in viruses. |
B. It is a gene that codes for growth factors that regulate the rate of cell division. |
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Which of the following best describes cancer cells? A. They are more highly differentiated than normal cells. |
C. Controls governing cell division have been altered. |
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Which of the following genes inhibit cell division? A. proto-oncogenes |
C. tumor-suppressor genes |
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A cancer cell __________. A. uses fewer nutrients than a normal cell |
D. does not respond to the signals that control cell division |
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Most human cancers are __________. A. caused by an accumulation of mutations |
A. caused by an accumulation of mutations |
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The second-leading cause of death in most developed countries (following heart disease) is __________. A. radiation overexposure |
B. cancer |
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What is the deadliest cancer? A. prostate cancer |
D. lung cancer |
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A normal gene that, if muted, can lead to cancer is called a(n) |
proto-oncogene |
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A gene that causes a cell to become cancerous is called a(n) |
oncogene |
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A(n) _________ is a gene that encodes proteins that inhibit cell division. Such proteins normally help prevent cells from becoming cancerous. |
tumor-suppressor gene |
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A(n)______ is a protein that promotes cell division. In excess, such a protein may lead to cancer. |
growth factor |
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Which of the following codes for protein? |
A. genes |
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You are developing a new drug that damages the cells that provide the supportive structure required by a tumor. Which type of cell are you targeting? |
A. fibroblast |
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A tumor would not be able to have its own blood supply if it weren’t for which of the following? |
A. immune system cells D. endothelial cells |
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Which of the following appears to be true according to the current research? |
C. As the population of Helicobacter pylori decreases in the human body, cases of esophageal cancer increase. |
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Mendel formulated his principles of inheritance based on ________. |
B. observations on the outcomes of breeding experiments. The underlying processes were unknown at the time. |
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Mendel observed that pairs of alleles were separated or segregated in gametes and that they were rejoined in fertilization. We know that pairs of _____ are segregated in _____ and then are rejoined through fertilization. A. linked genes … meiosis |
C. homologous chromosomes … meiosis |
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As we now understand it, the Law of Independent Assortment applies _____. A. to all pairs of genes |
B. to pairs of genes that are on different chromosomes, but NOT to pairs of genes that are close together on the same chromosome |
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If you are a male, the Law of Independent Assortment indicates that your gametes contain _____. A. only the chromosomes and alleles you inherited from your father |
C. a random mix of the chromosomes you inherited from each parent |
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How have Mendel’s laws fared as we have learned more about cell biology and processes such as meiosis? A. Our new knowledge has confirmed all of Mendel’s predictions and laws. |
D. Our new knowledge has helped to explain some of the exceptions to Mendel’s laws of inheritance. |
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The scientific study of heredity is called _____. A. heredity |
B. genetics |
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An allele is __________. A. a type of chromosome |
E. an alternative version of a gene |
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A ____ is an inherited feature that varies from individual to individual |
character |
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A _____ is one particular variation of a character |
trait |
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A genetic cross involving parents that differ in a single character is called a |
monohybrid |
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Most human genes come in alternate versions called |
alleles |
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If an organism has two non-identical versions of a gene, the one that is expressed in the organism is called the ______ allele |
dominant |
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If an organism has two non- identical versions of a gene, that one that is not expressed in the organism is called the ______ allele |
Recessive |
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The physical traits of an organism are called its |
phenotype |
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The ______ is the genetic makeup of an organism. |
genotype |
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The physical traits of an organism are called its _____. A. genotype |
C. phenotype |
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GgTt pea plants can produce _____ type(s) of gamete(s), but a ggtt plant can produce _____ type(s) of gamete(s). A. two … one |
E. four … one |
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Seeds from a sexually reproducing plant are harvested and later planted under identical conditions. What characteristics should be expected of the resulting offspring? A. The seedlings should differ from each other, depending on the environmental conditions under which each is planted. |
E. The seedlings should differ from each other, depending on their genetic constitution. |
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Mendel worked _____. A. on the Human Genome Project |
B. in a monastery |
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A mating between a purebred purple-flowered pea plant and a purebred white-flowered pea plant would produce a(n) ______. A. hybrid |
A. hybrid |
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According to Mendel’s law of segregation, ______. A. gametes have one copy of each allele |
A. gametes have one copy of each allele |
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Round seeds (R) are dominant to wrinkled seeds (r), and yellow seeds (Y) are dominant to green seeds (y). What is the expected phenotypic ratio of a cross between an RrYy and an rryy individual? A. 1:1:1:1 |
A. 1:1:1:1 |
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A plant with the genotype AABbcc is __________. A. heterozygous for two different genes |
B. homozygous for two different genes |
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GgTt pea plants can produce _____ type(s) of gamete(s), but a ggtt plant can produce _____ type(s) of gamete(s). A. four … two |
B. four … one |
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In a dihybrid cross ratio, what is the probability of getting the genotype aa when you cross genotypes Aa and aa? A. 1/8 |
D. 1/2 |
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A mating between a purebred purple-flowered pea plant and a purebred white-flowered pea plant would produce a(n) ______. A. hybrid |
A. hybrid |
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According to Mendel’s law of segregation, ______. A. two alleles segregate into each gamete |
C. gametes have one copy of each allele |
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A couple has two female children. What is the probability that their next child will be male? A. 67% |
B. 50% |
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Close relatives who mate are more likely to have children with genetic diseases because __________. A. close relatives are genetically very different |
C. close relatives are likely to carry the same genetic disorders |
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Folk singer Woody Guthrie died of Huntington’s disease, a degeneration of the nervous system that is caused by an autosomal dominant allele. Which statement below must be true? A. His sons will die of Huntington’s disease but not his daughters. |
E. At least one of Woody Guthrie’s parents must have had Huntington’s disease also. |
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Why is it that men are responsible for the gender of their children? A. Men can only contribute a Y chromosome. |
B. Unlike women, who only contribute an X chromosome, men contribute either an X or a Y chromosome. |
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Color blindness is a recessive, sex-linked trait in humans that is located on the X chromosome. The color-blindness trait shows up only in males because __________. A. the X and Y chromosomes have different lengths |
C. males have only a single X chromosome and thus no wild-type allele to offset the recessive allele |
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The development of many different breeds of dogs from a single ancestor has been the result of _____. A. domestication |
B. artificial selection |
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In humans, the __________ determines the sex of the offspring because __________. A. male … the sperm can fertilize either a female egg or a male egg |
D. male … the male can contribute either an X or a Y chromosome |
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Why are human males much more likely than human females to inherit the recessive condition hemophilia (a failure of the blood to clot properly)? A. hemophilia is the wild type |
D. the gene for hemophilia is sex-linked |
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To determine the genotype of an individual who expresses a dominant trait, you would cross that individual with an individual who ______. A. is heterozygous for that trait |
C. is homozygous recessive for that trait |
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The parents of a child with unusual disease symptoms take the child to a doctor for help. The doctor suspects that the condition might have a genetic basis. She recommends that the child be taken to a specialty clinic where physicians and staff members are trained to diagnose genetic diseases and counsel parents. Ultimately, the child is diagnosed with a rare recessively inherited disease. The parents are tested for the gene, and both are found to be heterozygous. The parents want to have another child but are afraid this child will also be affected. A. 1/8 |
B. 1/4 |
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In general, the frequency with which crossing over occurs between two linked genes depends on __________. A. the phase of meiosis in which the crossing over occurs |
D. how far apart they are on the chromosome |
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If exon-skipping drugs ultimately show success in patients with muscular dystrophy, which of the following diseases would be most likely to also respond to their use? A. Multiple sclerosis, an autoimmune disease. |
B. Tay Sachs, a genetic disorder. |
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Which of the following is behind the concept of creating exon-skipping drugs? A. Improperly working genes can be replaced. |
D. Improperly working genes can be corrected. |
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Your cousin has Duchenne muscular dystrophy. Which of the following is true? A. His body does not produce dystrophin. |
A. His body does not produce dystrophin. |
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Just one error in the genetic code can lead to problems in protein creation because which of the following are being incorrectly coded for? A. amino acids |
A. amino acids |
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You are the head of the federal agency ultimately responsible for deciding if exon-skipping drugs are approved for use. Who do you work for? A. National Institutes of Health |
C. Food and Drug Administration |
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The evolution of populations due to chance is A. genetic variation. |
C. genetic drift. |
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If color is an inherited trait in beetles, and birds are more likely to eat brown beetles than green beetles, A. this causes the population to evolve due to gene flow. |
D. the frequency of the green allele will increase. |
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In a population with brown and green alleles for color, genetic drift A. has more effect on the evolution of a large population. |
E. has more effect on the evolution of a small population. |
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Color is an inherited trait in beetles. If brown beetles move into a population from a nearby island, which of the following statements is correct? A. Natural selection causes the frequency of the green allele to increase. |
C. Gene flow causes the frequency of the brown allele to increase. |
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Remember that color is an inherited trait in beetles. Which of the following is an example of natural selection? A. Green beetles leave more offspring than brown beetles because they are better at finding food. |
A. Green beetles leave more offspring than brown beetles because they are better at finding food. |
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The phrase Darwin used to describe his broad theory of evolution is "descent with ______" |
Modification |
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All of life is related through common ancestry, accounting for the ______ of life. |
unity |
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The ________ of life arises from the adaptation of the species to different habitats over long spans of time. |
diversity |
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Darwin proposed a mechanism for how evolution occurs, which he called _______ |
natural selection |
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Two key observations underlying natural selection are that members of a population vary in their __________ an that all species can produce more offspring that the environment can support. |
inherited traits |
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Darwin inferred that those organisms with traits best suited to the environment tend to leave more ________ than other members of a population. |
offspring |
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The unequal reproduction in a population leads to the gradual accumulation of ________ to the environment. |
adaptations |
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The human immune system cannot effectively suppress the HIV virus on its own. What key feature of HIV makes it so hard to beat? A. The HIV virus can survive harsh conditions for years as a dormant particle. |
B. The HIV virus has an extremely high rate of mutation. |
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Imagine that four people are infected with HIV from a common source (an infected blood sample). Initially, the patients’ HIV populations are genetically identical. By the time they develop full-blown AIDS, how would the viral populations of the four patients compare? A. Each patient’s viral population would be unique, specifically adapted to deal with—and overcome—his or her unique immune system responses. |
A. Each patient’s viral population would be unique, specifically adapted to deal with—and overcome—his or her unique immune system responses. |
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As proposed by Darwin, what sorts of traits are favored by natural selection? A. Any traits that are produced by mutation and can be inherited. |
D. Heritable traits that help individuals survive and reproduce more successfully than others in the same population. |
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Natural selection is best described as _____. A. a creative force that efficiently develops the best and simplest solutions for all problems in nature |
C. a filtering process that fine-tunes the traits of populations by sorting among existing, randomly produced variations |
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HIV has become an important source of mortality for humans. If AIDS persists as a major factor for humans for many generations in the future, natural selection theory predicts that _____. A. any heritable traits that help humans survive and reproduce in the presence of AIDS should become more frequent over time |
A. any heritable traits that help humans survive and reproduce in the presence of AIDS should become more frequent over time |
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Which one of the following was an assumption of Charles Darwin’s theory of natural selection? A. Earth is very young. |
E. Populations produce more offspring than their environment can support. |
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A population is __________. A. the number of organisms in a particular habitat |
D. a group of individuals of the same species occupying a given area |
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Evidence from molecular biology supports the theory of evolution by showing that __________. A. closely related animal species have similar geographic distributions |
E. closely related organisms have more similar DNA and proteins |
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Which of the following is a requirement for natural selection? A. low numbers of individuals |
C. variation in individuals |
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"Differential success in reproduction" is just another way of saying _____. A. recombination |
E. natural selection |
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Which one of the following statements most closely agrees with the theory of evolution by means of natural selection, as put forth by Darwin? A. Organisms mutate under unfavorable conditions to become better adapted. |
B. Organisms better adapted to their immediate environment are most likely to survive and reproduce. |
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The smallest unit that can evolve is a _____. A. species |
C. population |
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The population of American bison used to number in the millions of animals. Hunting and other problems greatly decreased the number of bison to about 1,000 animals. But today, the numbers are recovering to estimates of more than 200,000 animals. This crash in the population of bison and recent recovery is a good example of _____. A. stabilizing selection |
B. the bottleneck effect |
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Imagine that a new population of humans is established on a new planet from ten randomly selected people in your biology class. Over thousands of years, the descendants of those ten people reproduce and prosper, but do not reflect well the diversity of humans on Earth. This change in the diversity of people on the new planet is an example of _____. A. the bottleneck effect |
E. the founder effect |
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Natural selection can be defined as ______. A. the production of more offspring than can survive in a given environment |
D. a process in which organisms with certain inherited traits are more likely to survive and reproduce than individuals with other traits |
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The wing of a bat is homologous to the _____ of a whale. A. flipper |
A. flipper |
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________ favors intermediate phenotypes, selecting against phenotypes at both ends of a range and reducing variation. |
stabilizing selection |
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__________ favors phenotypes at both ends of a range over intermediate phenotypes. This type of selection may occur when the habitat is varied. |
Disruptive selection |
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________ favors phenotypes at one end of a range and is common in periods of environmental change. |
Directional selection |
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In sexual selection, individuals with certain inherited characteristics are more likely to obtain mates than other individuals. This often results in __________, differences between the sexes in size, appearance, and behavior. |
sexual dimorphism |
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__________ is a type of sexual selection in which individuals of one sex (usually males) compete directly for mates. This may involve ritualized displays or physical combat. |
intrasexual selection |
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in a type of sexual selection often called _______, individuals of one sex (usually females) are choosy in selecting their mates. This choice is often based on the showy appearance or behavior of the male. |
mate choice |
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Sickle- cell disease is caused by ___________ |
C. a recessive allele |
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After surviving a bottleneck, a population recovers to the point where it consists of as many individuals as it did prior to the bottleneck. Which of the following statements is most likely to apply to this population? A. The bottleneck subjected the population to stabilizing selection. |
B. The postbottleneck population exhibits less genetic variation than the prebottleneck population. |
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What does evolutionary fitness measure? |
A. relative reproductive success |
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When they were first sold, aerosol insecticides were highly effective in killing flies and mosquitoes. Today, some 30 years later, a much smaller proportion of these insects die when sprayed. The reason fewer insects are being killed is that __________. A. the original spraying has caused a permanent mutation, giving the insects genetic resistance to the spray |
D. many mosquitoes today are descendants of mosquitoes with insecticide-resistant characteristics |
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Scientists have warned doctors of the danger of their increasing use of antibiotics (for instance, penicillin) for treating minor illnesses. They are concerned because _____. A. excessive use of these drugs leads to a diminished sensitivity to them |
B. strains of microorganisms that are resistant to these drugs will increase |
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In a population of bears, which is most likely to be considered to have the greatest Darwinian fitness? A. the biggest bear |
C. the bear that leaves the most descendants |
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A process in which organisms with certain inherited characteristics are more likely to survive and reproduce than individuals with other characteristics is called _____. A. evolution |
C. natural selection |
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Which one of the following was an assumption of Charles Darwin’s theory of natural selection? A. Traits are inherited as discrete particles. |
B. Populations produce more offspring than their environment can support. |
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Natural selection __________. A. relies on variation among individuals in a population |
A. relies on variation among individuals in a population |
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There is a group of small fish living in a lake with a sandy bottom. Most of the fish are light brown, but about 10% are mottled. These fish are normally prey for large birds that live on the shore. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance. Which of these statements presents the most accurate prediction? A. There is no way to guess the result. |
B. The proportion of mottled fish will increase over time. |
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Which of the following is an example of natural selection that has been seen in our lifetime? A. the evolution of antibiotic-resistant bacteria |
A. the evolution of antibiotic-resistant bacteria |
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In 1859, Charles Darwin wrote, "The affinities of all the beings of the same class have sometimes been represented by a great tree… As buds give rise by growth to fresh buds, and these if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications." At the base of the evolutionary tree of all life is ______________. A. an amniote |
D. an organism that is a common ancestor to all living organisms. |
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The population of American bison used to number in the millions of animals. Hunting and other problems greatly decreased the number of bison to about 1,000 animals. But today, the numbers are recovering to estimates of more than 200,000 animals. This crash in the population of bison and recent recovery is an example of _____. A. the bottleneck effect |
A. the bottleneck effect |
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Imagine that a new population of humans is established on a new planet from ten randomly selected people in your biology class. Over thousands of years, the descendants of those ten people reproduce and prosper, but do not reflect well the diversity of humans on Earth. This change in the diversity of people on the new planet is an example of _____. A. genetic drift |
B. the founder effect |
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In evolutionary terms, an organism’s Darwinian fitness is measured by its __________. A. mutation rate |
B. contribution to the gene pool of the next generation |
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Sickle-cell disease is caused by __________. A. the parasite that also causes malaria |
C. a recessive allele |
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