Deck 11: Stem Cells, Cancer, and Human Health

Question 1

Which of the following is not true of cell division?

A)A cell has no control over how often it divides.
B)Negative growth regulators are used to halt cell division.
C)Numerous cellular proteins are affected by cell division signals.
D)Uncontrolled cell division can cause cancer.

Answer 1

A

Question 2

In the 1960s, biologists successfully manipulated a cell from the leaf of a carrot to grow to become a fully complete carrot plant. What term best describes the growth potential of that manipulated cell?

A)totipotent
B)pleuripotent
C)unipotent
D)multipotent

Answer 2

A

Question 3

The number of stem cells appears to gradually decline with age; if so, how might this decline be explained?

A)To maintain a stable number of stem cells, one daughter cell of each division would need to revert back to a stem cell; the rate of reversion must decline with age.
B)Lacking specialization, stem cells must become more susceptible to disease processes than normal cells; eventually this susceptibility reduces their number.
C)As they age, stem cells evidently lose their vitality, quit dividing, and die of old age without leaving any additional daughter cells.
D)Continuous division with progressively shortened telomeres eventually produces a stem cell with critically missing DNA and a loss of an ability to further divide.

Answer 3

A

Question 4

Human males continuously produce sperm and remain fertile throughout their lives; this ability is most likely the result of

A)large quantities of immature sperm cells produced and stored in the testes early in life that gradually mature.
B)a hormonally based signal transduction pathway that converts testicular tissue into iPSCs.
C)the activity of multipotent stem cells in the testes.
D)the conversion of surplus cell types, like red blood cells, into sperm.

Question 5

In the illustration below, which letter correctly identifies the inner cell mass?

A)A
B)B
C)C
D)The inner cell mass is not labeled in this illustration.

Question 6

Stem cells display two unique characteristics: the ability to _____ and _____.

A)eliminate their telomeres; demonstrate anchorage dependence
B)differentiate into a variety of cell types; divide repeatedly
C)express genes; synthesize proteins
D)metastasize; initiate angiogenesis

Question 7

What statement(s)best describes the status of viral delivery of induced pluripotent stem cells (iPSCs)?

A)Testing in human subjects has yet to occur and is not imminent.
B)Cell cultures using human skin cells have been successfully developed.
C)Mammalian animal models have experienced mixed success and treated mice appear more susceptible to developing cancer than mice treated with embryonic stem cells.
D)all of the above

Question 8

The illustration below shows bone marrow stem cells; it is most likely that these stem cells are _____ because they are derived from _____.

A)totipotent; mesenchymal embryonic tissue
B)pluripotent; tissues that do not contribute to the production of the placenta or embryonic membranes
C)multipotent; a mature organ system that already shows differentiation
D)totipotent; the inner cell mass of the bone marrow

Question 9

What term(s)would describe the stem cell depicted in the illustration below?

A)totipotent or pluripotent
B)multipotent or unipotent
C)totipotent or multipotent
D)hemipotent or unipotent

Question 10

Which of the following is not likely to cause a cell to become cancerous?

A)mutation
B)meiosis
C)chemical pollutants
D)cigarette smoke

Question 11

Tissue containing totipotent embryonic stem cells is difficult to obtain; what is the usual source?

A)tissues from spontaneous miscarriage during the first trimester of pregnancy
B)the donation of surplus blastocysts produced by in vitro fertilization for women seeking fertility treatment
C)tissue from elective abortion during the first trimester of pregnancy
D)blood and/or tissue extracted from the placenta after the birth of the fetus

Question 12

Rapid cell proliferation can result from

A)contact inhibition.
B)a cell ignoring a negative growth regulator.
C)a mutation inhibiting the action of a positive growth regulator.
D)the surgical removal of a benign polyp.

Question 13

The illustration below shows the developmental sequence leading to an adult human. Every step, except one, requires that mitosis occur; the one exception is

A)fetus to adult.
B)zygote to morula.
C)blastocyst to embryo.
D)egg and sperm to zygote.

Question 14

A variety of therapies using adult stem cells have already been developed; for example, adult stem cells are currently used to

A)produce insulin for diabetics whose insulin-producing pancreas cells have lost that ability.
B)supplement dopamine production for individuals suffering from Parkinson's disease.
C)generate replacement neurons for individuals with spinal cord injuries.
D)regenerate worn cartilage in the knees and wrists of patients of osteoarthritis.

Question 15

Which statement best summarizes the capabilities of mammalian pluripotent stem cells?

A)Pluripotent cells can produce all cell types found in the body of an adult.
B)Pluripotent cells can produce all cell types found in the body of an organism, including the protective membranes that surround the embryo.
C)Pluripotent cells can produce all cell types found in the organ of their origin.
D)Pluripotent cells can produce all somatic cell types found in the body of an adult, but not germ cells.

Question 16

Explaining the differentiation of the numerous cell types in a mature organism from the initial zygote has been challenging. Which statement best summarizes the current understanding of the process?

A)Selective DNA replication; prior to cell division, only the DNA appropriate for the daughter cells' intended differentiation becomes available.
B)Selective chromosome movement; daughter cells receive only those chromosomes containing the appropriate genes required for their differentiation during cell division.
C)Selective gene expression; only specific genes are activated in particular cells.
D)Selective survival; only those cells randomly producing the appropriate protein survive, the remainder undergo apoptosis.

Question 17

Chemical manipulation in some instances can activate totipotency, but to recover a naturally totipotent cell, researchers need access to cells from the _____ days following fertilization.

A)gastrula, a structure developing within 14
B)blastula, a structure developing within 8-10
C)blastocyst, a structure developing within 5-7
D)morula, a structure developing within 3-4

Question 18

Substantial evidence suggests that differentiation signals influence the developmental pathway taken by stem cell daughter cells. From what sources might these signals arise?

A)the presence of specific adhesion molecules on neighboring cells
B)the internal genetic program inherited from the dividing adult stem cell itself
C)variations in the concentration of signal molecules involved in a signal transduction pathway
D)All of the above are reasonable hypotheses.

Question 19

The use of embryonic stem cells has generated great controversy in the United States because

A)embryonic stem cell products have a limited availability and seem to be more commonly distributed to those who can better afford to pay the high costs.
B)the treatments are considered experimental and are routinely rejected by insurance carriers.
C)such cells can only be harvested from human embryos, which many citizens believe have moral status and a unique life potential.
D)the U.S. government has enacted and maintains severe prohibitions regarding any research with these tissues.

Question 20

In the 1980s, biologists successfully transplanted the nucleus from a mammary gland cell of an adult sheep into an unfertilized egg of a second sheep, which after implantation in the uterus of a third sheep grew to become a fully complete baby lamb. What term best describes the growth potential of that nucleus?

A)totipotent
B)pluripotent
C)unipotent
D)multipotent

Question 21

When cells are stimulated to divide,

A)proto-oncogenes are inactivated.
B)tumor suppressors are activated.
C)tumor suppressors are inactivated.
D)oncogenes become proto-oncogenes.

Question 22

A protein is identified that starts a signal cascade leading to the activation of a gene that promotes cell division. This protein is coded for by a

A)tumor suppressor gene.
B)oncogene.
C)proto-oncogene.
D)carcinogen.

Question 23

The p53 protein is critical to the regulation of the cell cycle because it

A)halts cell division when necessary, allowing the cell to repair damaged DNA.
B)causes cells with heavily damaged, unrepairable DNA to commit "suicide."
C)prevents the cell from dividing at inappropriate times.
D)all of the above

Question 24

Normal cellular genes that can be mutated into cancer-causing genes are known as

A)oncogenes.
B)growth factors.
C)proto-oncogenes.
D)viral proteins.

Question 25

The cells in many large polyps in the human colon usually contain

A)normal tumor suppressor genes and at least one oncogene.
B)one inactive and one active copy of a tumor suppressor gene and normal proto-oncogenes.
C)two inactive copies of a tumor suppressor gene and two proto-oncogenes.
D)two inactive copies of a tumor suppressor gene and one oncogene.

Question 26

A tumor suppressor is a(n)

A)negative growth regulator.
B)oncogene.
C)positive growth regulator.
D)sarcoma virus.

Question 27

As indicated in the diagram below, in many human colon tumors, the beginning of true malignancy is the result of

A)the loss of the TIP30 tumor suppressor gene.
B)the loss of the p53 tumor suppressor gene.
C)the loss of the APC tumor suppressor gene.
D)a mutation in the c-myc gene.

Question 28

If exposure to sunlight causes a mutation in a single proto-oncogene in a diploid cell so that it becomes hyperactive,

A)the remaining unmutated proto-oncogene will prevent the cell from becoming cancerous.
B)tumor suppressor cells will destroy the proteins made from the mutated gene.
C)the cell might produce a protein that pushes it into rapid cell division.
D)the mutated gene will be inactivated by phosphorylation.

Question 29

A tumor that has gained the ability to spread throughout the body, generally with life-threatening consequences, is known as a _____ tumor.

A)benign
B)polyp
C)malignant
D)growth-promoting

Question 30

The proteins synthesized from proto-oncogenes, which often participate in signal cascades, are typically active

A)only in Golgi bodies.
B)only on the cell's surface.
C)only in the cell's nucleus.
D)throughout the cell.

Question 31

When a mutant receptor protein no longer requires a growth factor to activate it, the result is

A)reduction in cell division.
B)extra binding sites.
C)uncontrolled cell division.
D)lack of protein products.

Question 32

Which of the following is not true of cancer?

A)Cancer involves cell proliferation.
B)Cancer can be caused by viruses.
C)Cancer results from a balanced production of positive and negative growth regulators.
D)Cancer involves the loss of a cell's ability to control cell division.

Question 33

Which of the following kinds of molecules are the least likely to be produced by a proto-oncogene?

A)receptor proteins
B)growth factors
C)protein kinases
D)ribosomal proteins

Question 34

A woman who has already had children develops skin cancer from overexposure to the sun. Is it possible for her children to have inherited this cancer from her?

A)No, because only mutations that occur in gametes can be passed on to the next generation.
B)No, because any cancer that develops after a person is an adult cannot have a genetic component.
C)Yes, because almost all cancers are caused by genetic factors.
D)Yes, because the woman's children have exactly the same genome as their mother does.

Question 35

Tumor suppressor proteins

A)produce growth factor signal cascades.
B)remove growth factors from DNA.
C)inactivate components of growth factor signal cascades.
D)are produced by growth factors.

Question 36

Proto-oncogenes, which produce many of the proteins used in a signal cascade, are found

A)only in Golgi bodies.
B)only on the cell's surface.
C)only in the cell's nucleus.
D)throughout the cell.

Question 37

If a cell's p53 genes are inactivated, the cell

A)loses control over cell division.
B)no longer makes proto-oncogenes.
C)stops dividing.
D)activates tumor suppressors.

Question 38

Normal cell division requires

A)inactivated proto-oncogenes and activated tumor suppressor genes.
B)inactivated proto-oncogenes and inactivated tumor suppressor genes.
C)activated proto-oncogenes and activated tumor suppressor genes.
D)activated proto-oncogenes and inactivated tumor suppressor genes.

Question 39

The fact that the human genome contains proto-oncogenes means that

A)there is nothing we can do to reduce our chance of developing cancer.
B)our genomes are constantly producing cancerous cells.
C)the disruption of certain cellular controls can lead to cancer.
D)we will all develop cancer during our lifetimes.

Question 40

For cancer to form in the presence of a tumor suppressor gene, which of the following is necessary?

A)Both copies of the tumor suppressor gene must be inactivated.
B)The tumor suppressor gene must be activated.
C)One copy of the tumor suppressor gene must be inactivated.
D)The tumor suppressor gene is not involved in cancer formation.

Question 41

Cancer in humans is caused

A)only by environmental factors.
B)only by genetic factors.
C)by neither environmental nor genetic factors.
D)by both environmental and genetic factors.

Question 42

For a virus to reproduce, it must insert its DNA into the host cell's genome. How might this cause cancer in the host?

A)The viral DNA could insert a gene that controls cell division into the host's DNA.
B)Because the host cell is much smaller than the virus, the host cell must expand until it becomes a tumor large enough to hold the virus.
C)The virus could turn off an oncogene.
D)Viruses cannot cause cancer.

Question 43

All the cells of the human body have the same genes, but because genes can be selectively ____________________, a variety of different cell types can form.

Question 44

Adult and embryonic stem cells share many similarities, but only ____________________ stem cells can give rise to all of the 220 cell types that occur in the human body.

Question 45

A mutated version of a virus that cannot disable the p53 gene can be used to

A)turn off the host cell's enzymatic activities.
B)repair defective genes.
C)turn off signal cascades.
D)kill cancer cells.

Question 46

A physical, chemical, or biological agent that causes cancer is called a(n)

A)virus.
B)carcinogen.
C)oncogene.
D)regulatory protein.

Question 47

Not all stem cells can generate all body cell types, only those described as ____________________ have this ability.

Question 48

HeLa cells display a variety of abnormalities. Which is most associated with their ability to divide repeatedly?

A)The cell line shows evidence of having been infected with HPV (human papillomavirus).
B)HeLa cells express the telomerase gene and are able to reconstruct the ends of their chromosomes after each round of cell division.
C)The cell line is quadraploid (having four sets of chromosomes) rather than diploid (having two sets of chromosomes) like all normal somatic cells.
D)The HeLa cell line was exposed to cosmic radiation prior to developing its unusual reproductive capabilities.

Question 49

Cell differentiation can be experimentally studied in the lab using a procedure known as ____________________ that allows a single variable to be manipulated.

Question 50

A ____________________ is a segment of DNA that encodes for a distinct inherited characteristic.

Question 51

The mesoderm, or middle tissue layer, of a mammal embryo can generate bone, cartilage, blood, and other connective tissues through the process of ____________________.

Question 52

The capacity of embryonic stem cells and HeLa cells to divide repeatedly suggests that they share one or more common features, the most important is probably the ability to synthesize ____________________ and repair their chromosomes after each round of cell division.

Question 53

Chemotherapy often produces hair loss and nausea. What aspect of the treatment impacts these normal nontarget tissues?

A)The cells that form the hair follicle and line the digestive system have receptors similar to those found on tumor cells and bind the chemotheraputic agents just as the tumor cells do.
B)All cells acquire the cytotoxic drugs but the cells that grow most rapidly, like hair cells and tumor cells, accumulate a lethal dose more quickly.
C)Cells that are damaged by chemotherapy are nonmutated versions of the tumor cells; both the normal and tumor cells retain their sensitivities to the chemotherapy and are equally affected.
D)Oncologists have no satisfactory explanation for the observation, but are working aggressively to minimize these and other unintended effects.

Question 54

Grilling meat appears to be associated with an avoidable exposure to carcinogens that form when

A)the growth hormones used by the livestock industry react at high temperature with meat proteins.
B)the antibiotics routinely used by the livestock industry degrade at high temperature.
C)certain amino acids and fats react at high temperature to form HCAs and PAHs.
D)combustion products from the charcoal, natural gas, or propane mutate the DNA in the cooked food.

Question 55

Although expensive, many health experts are in favor of extending free vaccinations for human papilloma virus (HPV)to males even though HPV infection is more inconvenient than life threatening. How might society benefit if both males and females receive free vaccinations?

A)Because the disease is sexually transmitted, fewer infected males will reduce the rate of transmission to their unvaccinated partners.
B)Epidemiological studies have shown that the most effective way to eliminate an infectious disease is to remove any reservoirs from which it can infect unvaccinated hosts.
C)It is a commonly experienced infection with health care costs that greatly exceed the cost of vaccination.
D)all of the above

Question 56

Which of the following statements about viruses is false?

A)Viruses can cause cancer.
B)Viruses can be used to destroy cancer cells.
C)Viruses do not contain a nucleic acid.
D)Viruses take over a cell's machinery to reproduce.

Question 57

Malignant cancers often require that a single cell experience as many as four mutations; does a single mutation predispose a cell to a second or third?

A)Yes, particularly if the first mutation depresses a DNA-correcting mechanism allowing subsequent injuries to remain uncorrected.
B)No, each cell is uniformly at risk for mutation; if a cell has four mutations, it likely that its neighbors have two or three.
C)Yes, initial mutations often lead to the construction of carcinogen receptors that pull harmful chemicals into the cell and accelerate the mutation process.
D)No, mutation is an entirely random process; carcinogens have no way of locating a previously damaged cell.

Question 58

Even though all people are exposed to potential carcinogens on a daily basis, we do not all develop cancer. Why?

A)The carcinogens are too weak to cause mutations in our DNA.
B)Human cells are resistant to carcinogens until we are approximately 50 years old.
C)DNA repair mechanisms are able to correct some of the mutations that occur.
D)Humans' oncogenes protect us from most of the carcinogens we are exposed to.

Question 59

Examine the graph below.
This graph shows that the

A)rate of cancer diagnosis increases for both genders with increasing age.
B)mortality rate for cancer increases more rapidly in older men than in older women.
C)probability of acquiring cancer for both genders becomes greater than 50 percent after age 80.
D)majority of individuals living to age 80 or beyond will be diagnosed with cancer.

Question 60

A pesticide was found to cause cancer in laboratory mice. Which of the following would be the most reasonable hypothesis to pursue?

A)The pesticide mutates an oncogene to a proto-oncogene.
B)The pesticide mutates both oncogenes to proto-oncogenes.
C)The pesticide mutates one oncogene to a proto-oncogene and one tumor suppressor gene to an inactive form.
D)The pesticide mutates both tumor suppressor genes to inactive forms.

Question 61

Cancer-causing chemicals increase the risk of cancer by promoting ____________________ in the DNA, causing changes in the DNA base sequences.

Question 62

Since the controversy involving stem cells recovered from embryos is essentially based on a misunderstanding of the cell recovery process, a better educational effort by advocates of the process should quickly allay any concerns.

Question 63

Cancer-causing genes are known as ____________________.

Question 64

Under normal conditions, growth factors activate ____________________ and inactivate ____________________ genes.

Question 65

Regenerative medicine and stem cell therapy promise a possible cure for ____________________ disease, a devastating neurological disorder marked by uncontrollable body movements.

Question 66

A harmless proliferation of cells in a human colon would be called a(n)____________________ polyp.

Question 67

The only source of noninduced totipotent human stem cells is the inner mass of the blastocyst, a structure that forms within a week of fertilization.

Question 68

Multipotency and unipotency can be a characteristic of some adult stem cell lines and develop when specific genes are deleted in the differentiation process.

Question 69

While HPV infection in women can lead to life-threatening cancer, in males infection typically results in ____________________.

Question 70

For proper cell division to occur, the activity of proto-oncogenes must be balanced by the activity of ____________________ genes.

Question 71

A variety of progressive stages characterize human embryogenesis, but the process always begins with the formation of a zygote.

Question 72

Mutations cause changes in ____________________ produced by a gene.

Question 73

A ____________________ is a harmless growth that may occur in the colon, for example, without being cancerous.

Question 74

Cancer cells cause tumors in other parts of the body by traveling through the ____________________.

Question 75

____________________ cancers spread throughout the body with life-threatening consequences.

Question 76

Unipotent stem cells can generate all the cells of the organ of their origin.

Question 77

Positive growth regulators increase the rate of ____________________.

Question 78

A physical, chemical, or biological agent that causes cancer is a ____________________.

Question 79

Even today relatively few human cells can be grown successfully in culture; the process began in the 1950s with the discovery of HeLa cells.

Question 80

____________________ starts with a single cell that loses its ability to control cell division.