Deck 8: The Cellular Basis of Reproduction and Inheritance

Question 1

Which of the following helps maintain the structure of chromosomes and control the activity of genes?

A) the nuclear membrane
B) proteins
C) centromeres
D) ribosomes

Answer 1

B

Question 2

At the start of mitotic anaphase

A) the centromeres of each chromosome come apart.
B) the chromatid DNA replicates.
C) nuclear envelopes begin to form around the chromosomes.
D) equivalent and complete collections of chromosomes have reached the two poles.

Answer 2

A

Question 3

The creation of genetically identical offspring by a single parent, without the participation of sperm and egg, is called

A) asexual reproduction.
B) sexual reproduction.
C) regeneration.
D) spontaneous generation.

Answer 3

A

Question 4

Which of the following statements regarding cell division is false?

A) Cell division can reproduce an entire organism.
B) Cell division is necessary for development to occur.
C) Cell division is the basis of both sexual and asexual reproduction.
D) Cell division is common in eukaryotes but rare in prokaryotes.

Question 5

The phase of mitosis during which the mitotic spindle begins to form is

A) interphase.
B) prophase.
C) metaphase.
D) anaphase.

Question 6

Eukaryotic chromosomes differ from prokaryotic chromosomes in that they

A) are simpler.
B) are circular in structure.
C) include fewer proteins.
D) are housed in a membrane-enclosed nucleus.

Question 7

Which of the following occurs during interphase?

A) a reduction in the size of the nuclear membrane
B) cytokinesis
C) cell growth and duplication of the chromosomes
D) separation of newly formed DNA to opposite ends of the cell

Question 8

With the exception of identical twins, siblings who have the same two biological parents are likely to look similar, but not identical, to each other because they have

A) identical chromosomes but different genes.
B) identical genes but different chromosomes.
C) the same combination of traits but different genes.
D) a similar but not identical combination of genes.

Question 9

Prior to mitosis and after S phase, each chromosome of a eukaryotic cell consists of a pair of identical structures called

A) chromatin.
B) sister chromosomes.
C) nucleoli.
D) sister chromatids.

Question 10

The genetic material is duplicated during

A) the mitotic phase.
B) G1.
C) the S phase.
D) G2.

Question 11

Strictly speaking, the phrase "like begets like" refers to

A) all forms of reproduction.
B) sexual reproduction only.
C) asexual reproduction only.

Question 12

Asexual reproduction requires ________ individual(s), whereas sexual reproduction requires ________ individual(s).

A) 1; 1
B) 1; 2
C) 2; 1
D) 2; 2

Question 13

The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called

A) mitosis.
B) cytokinesis.
C) binary fission.
D) telophase.

Question 14

Sister chromatids are

A) found immediately after a cell divides.
B) joined together at a centromere.
C) made only of DNA.
D) unique to prokaryotes.

Question 15

Eukaryotic cells spend most of their cell cycle in which phase?

A) interphase
B) prophase
C) metaphase
D) telophase

Question 16

Looking into your microscope, you spot an unusual cell. Instead of the typical rounded cell shape, the cell has a very narrow middle separating two bulging ends. It sort of looks like the number 8! You realize that this cell is

A) undergoing cytokinesis.
B) in the S phase of interphase.
C) in the G1 phase of interphase.
D) about to undergo mitosis.

Question 17

During which phase of mitosis does the nuclear envelope re-form?

A) anaphase
B) metaphase
C) prophase
D) telophase

Question 18

Which of the following statements regarding sexual and asexual reproduction is true?

A) Cell division only occurs after sexual reproduction.
B) Only offspring from asexual reproduction inherit traits from two parents.
C) Sexual reproduction typically includes the development of unfertilized eggs.
D) Sexual reproduction is more likely to increase genetic variation than is asexual reproduction.

Question 19

Which of the following statements regarding prokaryotes is false?

A) Prokaryotic chromosomes are more complex than those of eukaryotes.
B) Most prokaryotes reproduce by binary fission.
C) Prokaryotic cells are generally smaller and simpler than eukaryotic cells.
D) In prokaryotes, daughter chromosomes are separated by an active movement away from each other and the growth of a new plasma membrane between them.

Question 20

During which phase of mitosis do the chromosomes line up on a plane equidistant from the two spindle poles?

A) prophase
B) metaphase
C) anaphase
D) telophase

Question 21

As a patch of scraped skin heals, the cells fill in the injured area but do not grow beyond that. This is an example of

A) density-independent inhibition.
B) density-dependent inhibition.
C) anchorage independence.
D) growth factor inhibition.

Question 22

Which of the following features likely accounts for the difference between plant and animal cell cytokinesis?

A) Animal cells lack the microfilaments required for forming a cleavage furrow.
B) Animal cells lack chloroplasts.
C) Plant cells have cell walls.
D) Plant cells have two sets of chromosomes; animal cells have one set of chromosomes.

Question 23

Both mitosis and meiosis are preceded by

A) prometaphase.
B) interphase.
C) prophase.
D) telophase.

Question 24

You are asked to culture an unidentified sample of animal tissue. You notice that the cells seem to fail to exhibit density-dependent inhibition. The source of this tissue sample is most likely

A) a cancerous tumor.
B) skin from a human.
C) liver from a cow.
D) sperm-producing tissue of the testis.

Question 25

Mature human neuron (nerve) cells and muscle cells

A) become cancerous more easily than other cell types.
B) continue to divide throughout their lifetime.
C) are permanently in a state of nondivision.
D) cease dividing after a predetermined number of cell generations.

Question 26

Which of the following is a feature of plant cell division that distinguishes it from animal cell division?

A) formation of a cell plate
B) formation of a cleavage furrow
C) lack of cytokinesis
D) production of four (rather than two) new cells per mitotic division

Question 27

Which of the following statements correctly describes the behavior of a tetrad during anaphase I of meiosis?

A) It travels intact to one pole of the dividing cell.
B) It splits into two pairs of sister chromatids, and one pair goes to each pole of the dividing cell.
C) It splits into two pairs of homologous, nonsister chromatids, and one pair goes to each pole of the dividing cell.
D) It splits into four chromosomes, which distribute in random pairs to the two poles of the dividing cell.

Question 28

A pair of sex chromosomes found in a human male is most like

A) a pair of blue jeans.
B) a bride and groom.
C) a knife, fork, and spoon.
D) identical twins.

Question 29

Which of the following is probably the main factor responsible for the phenomenon of density-dependent inhibition?

A) a local accumulation of growth-inhibiting factors
B) cells' innate ability to "sense" when the organ of which they are a part has no need for additional cells
C) a local deficiency of nutrients
D) physical contact of cell-surface proteins between adjacent cells

Question 30

Which of the following statements regarding the differences between mitosis and meiosis is false?

A) In meiosis four daughter cells are produced, whereas in mitosis two daughter cells are produced.
B) In mitosis cytokinesis occurs once, whereas in meiosis cytokinesis occurs twice.
C) Crossing over is a phenomenon that creates genetic diversity during mitosis.

Question 31

Two chromosomes in a nucleus that carry genes controlling the same inherited characteristics are

A) homologous chromosomes.
B) sister chromatids.
C) complementary chromosomes.

Question 32

Which of the following shows the greatest promise as a cancer chemotherapy agent?

A) a drug that interferes with organismal cellular respiration
B) a drug that prevents mitotic spindle from forming
C) a drug that prevents crossing over
D) a drug that prevents tetrad formation

Question 33

Which of the following must occur for a plant or animal to grow and develop normally?

A) The organism must receive a supply of the appropriate hormones from its parents.
B) The organism must be able to control the timing and rate of cell division in different parts of its body.
C) Sufficient light must be available to stimulate cell division.
D) Sufficient oxygen must be available to stimulate cell division.

Question 34

Which of the following statements regarding mitosis and meiosis is false?

A) In animals, meiosis only occurs in the ovaries and testes.
B) All sexual life cycles involve an alternation of diploid and haploid stages.
C) Mitosis produces daughter cells with half the number of chromosomes as the parent cell.
D) A normal human zygote has 46 chromosomes.

Question 35

Which of the following statements regarding the cell cycle control system is false?

A) The cell cycle control system receives messages from outside the cell that influence cell division.
B) The cell cycle control system triggers and controls major events in the cell cycle.
C) The cell cycle control system includes three key checkpoints to complete a cell cycle.
D) The cell cycle control system operates independently of the growth factors.

Question 36

When animal cells are grown in a petri dish, they typically stop dividing once they have formed a single, unbroken layer on the bottom of the dish. This arrest of division is an example of

A) mitosis S phase.
B) density-dependent inhibition.
C) lack of nutrients.

Question 37

Which of the following statements is false?

A) Gametes are haploid cells.
B) Two haploid cells fuse during fertilization.
C) An X chromosome is an autosome.
D) A zygote is a fertilized egg.

Question 38

A benign tumor differs from a malignant tumor in that a benign tumor

A) is cancerous.
B) spreads from the original site.
C) does not metastasize.
D) never causes health problems.

Question 39

Which of the following statements regarding mitosis and meiosis is false?

A) Mitosis provides for growth and tissue repair.
B) Meiosis provides for asexual reproduction.
C) In mitosis, the chromosomes replicate only once in the preceding interphase.
D) All the events unique to meiosis occur during meiosis I.

Question 40

Which of the following statements regarding the function of mitosis is false?

A) Mitosis allows organisms to grow.
B) Mitosis promotes genetic diversity.
C) Mitosis is necessary for asexual reproduction in eukaryotes.
D) Mitosis promotes repair tissues.

Question 41

You are observing a single cell under a microscope. You go home for the night, and the next day you see four cells. The four cells look similar, and when you stain them with a dye that binds to DNA they all appear to contain the same amount of DNA as the original cell. What likely happened overnight?

A) The single cell divided once to form four new cells via asexual reproduction.
B) The single cell divided once to form four new cells via sexual reproduction.
C) The single cell divided to form two new cells, and the two new cells each divided to form four total cells, all by asexual reproduction.
D) The single cell divided to form two new cells, and the two new cells each divided to form four total cells, all by sexual reproduction.

Question 42

Jacobsen syndrome, which can cause heart defects, intellectual deficiencies, and bleeding disorders, is caused by a deletion of the terminal end of chromosome 11. What method could you use to determine whether an individual has Jacobsen syndrome?

A) Look at a person's skin cells in G1 under a light microscope.
B) Perform a karyotype using a person's white blood cells.
C) Place a person's red blood cells in culture to see if they grow.
D) Count the number of chromosomes present.

Question 43

Which of the following types of organisms commonly demonstrates polyploidy?

A) mammals
B) reptiles
C) flowering plants
D) fish

Question 44

A karyotype is most like

A) a map showing the hidden location of buried treasure.
B) a movie showing the stages of the reproductive cycle of a beetle.
C) photographs of every couple at a high school prom.
D) the answer key to a multiple-choice exam.

Question 45

Karyotyping

A) shows chromosomes as they appear in metaphase of meiosis II.
B) can reveal alterations in chromosome number.
C) examines points of crossing over.
D) reveals the presence of cancerous genes.

Question 46

You have two flasks (labeled A and

A) The cells in flask A will have grown significantly, but the cells in flask B will have not grown at all.
B) The cells in both flasks A and B will have grown significantly.
B) that each contain an equal population of normal animal cells. You place flask A in a machine called a shaking incubator, which shakes the flask at 37°C and keeps the cells moving so as to not allow them to adhere to the bottom of the flask. Flask B is allowed to sit in an incubator (without shaking) at 37°C. If you let the cells in each flask grow for a week, which of the following results are you most likely to observe?
C) The cells in both flasks A and B will have not grown at all.
D) The cells in flask B will have grown significantly, but the cells in flask A will have not grown at all.

Question 47

Nondisjunction occurs when

A) a portion of a chromosome breaks off and is lost.
B) two chromosomes fuse into one.
C) members of a chromosome pair fail to separate.
D) an entire pair of chromosomes is lost during meiosis I.

Question 48

Independent orientation of chromosomes at metaphase I results in an increase in the number of

A) gametes.
B) homologous chromosomes.
C) possible combinations of characteristics.
D) sex chromosomes.

Question 49

A cell that has a cell wall is undergoing cell division, and the following events are observed: the formation of a cell plate and the division of the cell into two daughter cells. What type of cell is being observed and what process(es) is it going through?

A) prokaryote; telophase of mitosis
B) animal cell; telophase and cytokinesis of mitosis
C) plant cell; telophase and cytokinesis of mitosis
D) plant cell; telophase II of meiosis

Question 50

Which of the following statements regarding Down syndrome is false?

A) Trisomy 21 is the cause of Down syndrome.
B) Down syndrome is the most common serious birth defect in the United States.
C) People with Down syndrome usually have a shorter life span than normal.
D) Down syndrome is least likely to be seen in the infants of mothers over 40.

Question 51

Cancer is not usually inherited because

A) the chromosomal changes in cancer are usually confined to somatic cells.
B) people with cancer usually die before reproducing.
C) the causes of cancer are not usually genetic.
D) the cancerous cells usually interfere with the ability to produce gametes.

Question 52

Below are three statements. Classify them as examples of independent orientation, crossing over, or random fertilization. I: The formation of a zygote from an egg and a sperm is an unpredictable event.
II: Random combinations of paternal and maternal chromosomes end up in gametes.
III: An allele on the paternal chromosome 18 ends up on the maternal chromosome 18.

A) I: random fertilization; II: random fertilization; III: independent orientation
B) I: random fertilization; II: crossing over; III: independent orientation
C) I: independent orientation; II: random fertilization; III: crossing over
D) I: random fertilization; II: independent orientation; III: crossing over

Question 53

A skin cell of a red fox has 34 chromosomes. You look at the cell under a microscope and see that it has 34 chromosomes and one nucleus. Several hours later, you look at the same cell again and see that it has double the amount of DNA and one nucleus. A little while later, you see that it has 68 chromosomes and two nuclei. What stage of the cell cycle was this cell in when you viewed it at each time point?

A) First view: G1; second view: G2; third view: telophase
B) First view: G1; second view: metaphase; third view: cytokinesis
C) First view: S; second view: prophase; third view: cytokinesis
D) First view: G0; second view: G2; third view: telophase

Question 54

If a chromosome fragment breaks off and then reattaches to the original chromosome but in the reverse direction, the resulting chromosomal abnormality is called a(n)

A) deletion.
B) inversion.
C) translocation.
D) reciprocal translocation.

Question 55

How many generations does it take to develop a new plant species by polyploidy?

A) 1
B) 2
C) 10
D) 20

Question 56

When observing a bird skin cell in G2 under a microscope, you count 160 total chromatids. How many chromosomes does a male chicken have in its sperm cells?

A) 320
B) 160
C) 80
D) 40

Question 57

Which of the following variations of the sentence "Where is the cat?" is most like a chromosomal inversion?

A) Where is cat?
B) Where is the the cat?
C) Where the is cat?
D) Where is cat the the cat?

Question 58

Which of the following statements regarding mitosis and meiosis is true?

A) Sister chromatids separate during anaphase of mitosis and anaphase II of meiosis.
B) Mitosis takes place in your gametes, whereas meiosis takes place in your somatic cells.
C) In metaphase of mitosis and metaphase I of meiosis, homologous chromosomes separate.
D) Independent orientation occurs during metaphase of mitosis and metaphase II of meiosis.

Question 59

You and your lab partner are observing a cell under a microscope, but you do not know whether it is a eukaryote or a prokaryote. Which of the following observations regarding the chromosomes would you use to immediately conclude that the cell is a eukaryote?

A) The chromosomes are circular in structure.
B) The chromosomes are housed in a membrane-enclosed nucleus.
C) The chromosomes contain very few proteins.
D) The chromosomes are very simple in structure.

Question 60

At a chiasma, two ________ are attached to each other.

A) homologous or nonsister chromatids
B) homologous or sister chromatids
C) nonhomologous chromosomes
D) daughter cells

Question 61

A technique called flow cytometry is used by scientists and researchers to count or sort cells based on specific properties. By labeling cellular DNA with a fluorescent dye, flow cytometry can sort cells based on the amount of DNA present, thereby making it possible to distinguish between cells that are in different stages of the cell cycle. Flow cytometry is especially useful to the medical community because it can help with the diagnosis of certain types of cancers. Below is a typical set of data that you might obtain when running a flow cytometry experiment using a sample of healthy skin cells. Use this figure to help you answer the following questions. After reading the paragraph below, answer the questions that follow.
If you used flow cytometry to sort a sample of cancerous cells that have been treated with a drug to prevent them from replicating their DNA, what peaks would you expect to see on the resulting flow cytometry data set?

A) A only
B) C only
C) A and B only
D) A, B, and C

Question 62

Plants grow taller through mitosis at the tips of their shoots (above ground) and at the tips of their roots (below ground). Here are two samples of tissue taken from a grass plant, one from the tip of the root and one from the mid part of the plant.
$\begin{array} { | l | l | l | } \hline \text { Stage } & \text { Sample 1 } & \text { Sample 2 } \\\hline \text { Interphase } & 74 \% & 98 \% \\\hline \text { Prophase } & 18 \% & 0.5 \\\hline \text { Metaphase } & 4 \% & 0.2 \% \\\hline \text { Anaphase } & 2 \% & 0.1 \% \\\hline \text { Telophase } & 1 \% & 0.1 \% \\\hline\end{array}$

-What can you conclude from these data?

A) Sample 1 is likely from tissue in the middle of the plant because most cells are in interphase.
B) Sample 2 is likely from tissue in the middle of the plant because there are fewer cells in telophase than are in prophase
C) Sample 2 is likely from tissue in the middle of the plant because fewer cells are in any mitotic stage.
D) Sample 1 is likely from tissue in the middle of the plant because fewer cells are in any mitotic stage than in sample 2.

Question 63

Use the figure below to answer the questions that follow.
Source: Adapted from C. A. Huether et al., Maternal age specific risk rate estimates for Down syndrome among live births in whites and other races from Ohio and Metropolitan Atlanta, 1970-1989, Journal of Medical Genetics 35: 482-90 (1998). Figure 8.20B Maternal age and incidence of Down syndrome
You are studying chromosomal movement in a frog species whose haploid number is 3. What will you see in meiosis I prophase of this cell?

A) three chromosomes, each made up of sister chromatids (double-stranded)
B) six chromosomes, each made up of sister chromatids (double-stranded)
C) three chromosomes, each single-stranded (unduplicated)

Question 64

Use the figure below to answer the questions that follow.
Source: Adapted from C. A. Huether et al., Maternal age specific risk rate estimates for Down syndrome among live births in whites and other races from Ohio and Metropolitan Atlanta, 1970-1989, Journal of Medical Genetics 35: 482-90 (1998). Figure 8.20B Maternal age and incidence of Down syndrome
What is the stage of cell division in a diploid organism if you see seven chromosomes, each consisting of a pair of sister chromatids?

A) mitosis prophase
B) mitosis anaphase
C) meiosis I anaphase
D) meiosis II prophase

Question 65

After reading the paragraphs below, answer the questions that follow.
Mr. and Mrs. Smith have three sons in elementary school. Two of their children are progressing normally, but their youngest son, Charles, has been much slower than his siblings in developing speech and language skills. His parents are concerned that he has a learning disability and decide to investigate further. Since some learning disabilities can be genetically based, their pediatrician recommends a chromosomal analysis.
The results show that Charles has a trisomy of the sex chromosomes, diagnosed as XYY. A mistake during sperm formation resulted in an extra copy of the Y chromosome. The extra copy was passed on to Charles during fertilization. Most often, this chromosomal change causes no unusual physical features or medical problems, but those with trisomy of the sex chromosomes may have a higher-than-normal risk of delays in learning development.
During which stage of meiosis could this mistake have occurred?

A) telophase I
B) prophase I
C) anaphase II
D) telophase II

Question 66

If the four cells shown resulted from cell division of a single cell with diploid chromosome number 2n = 4, what best describes what just occurred?

A) normal meiosis
B) translocation
C) inversion
D) nondisjunction

Question 67

Use the figure below to answer the questions that follow.
Source: Adapted from C. A. Huether et al., Maternal age specific risk rate estimates for Down syndrome among live births in whites and other races from Ohio and Metropolitan Atlanta, 1970-1989, Journal of Medical Genetics 35: 482-90 (1998). Figure 8.20B Maternal age and incidence of Down syndrome
If scientists studying cancer could understand how to promote cell division in cells that do not ordinarily divide, this might help people who had injuries involving

A) muscle or nerve cells.
B) intestinal cells.
C) bone cells.
D) skin cells.

Question 68

You are a medical student and are reviewing a case study about a past patient. The patient was 4 feet 8 inches tall at age 38, was unable to have children, and had cognitive impairments. The patient also had an irregular number of chromosomes. What diagnosis would you give the patient?

A) Turner syndrome
B) Down syndrome
C) Klinefelter syndrome
D) chronic myelogenous leukemia

Question 69

What event will immediately follow the event shown in the following image?

A) The cell will divide into two animal cells.
B) The cell will divide into two plant cells.
C) The cell will enter metaphase.
D) The cell will enter prophase.

Question 70

Use the figure below to answer the questions that follow.
Source: Adapted from C. A. Huether et al., Maternal age specific risk rate estimates for Down syndrome among live births in whites and other races from Ohio and Metropolitan Atlanta, 1970-1989, Journal of Medical Genetics 35: 482-90 (1998). Figure 8.20B Maternal age and incidence of Down syndrome
Many cancer drugs known as "antimitotics" target microtubules. What is the first stage of mitosis at which these drugs are likely to have an effect?

A) anaphase
B) metaphase
C) prophase
D) telophase

Question 71

According to the graph, at what maternal age is the incidence of Down syndrome equal to five times the incidence at age 40?

A) about 29 or 30
B) about 35 or 36
C) about 44 or 45
D) about 46 or 47

Question 72

A technique called flow cytometry is used by scientists and researchers to count or sort cells based on specific properties. By labeling cellular DNA with a fluorescent dye, flow cytometry can sort cells based on the amount of DNA present, thereby making it possible to distinguish between cells that are in different stages of the cell cycle. Flow cytometry is especially useful to the medical community because it can help with the diagnosis of certain types of cancers. Below is a typical set of data that you might obtain when running a flow cytometry experiment using a sample of healthy skin cells. Use this figure to help you answer the following questions. After reading the paragraph below, answer the questions that follow.
Which peak represents cells that contain the most DNA?

A) A
B) B
C) C
D) It cannot be determined from this figure.

Question 73

Use the figure below to answer the questions that follow.
Source: Adapted from C. A. Huether et al., Maternal age specific risk rate estimates for Down syndrome among live births in whites and other races from Ohio and Metropolitan Atlanta, 1970-1989, Journal of Medical Genetics 35: 482-90 (1998). Figure 8.20B Maternal age and incidence of Down syndrome
You see a cell with several nuclei and you know that something is different about cell division. What is the most likely explanation?

A) failure of cytokinesis following mitosis
B) failure of sister chromatids to separate
C) nondisjunction
D) failure of homologous chromosomes to separate

Question 74

Use the figure below to answer the questions that follow.
Source: Adapted from C. A. Huether et al., Maternal age specific risk rate estimates for Down syndrome among live births in whites and other races from Ohio and Metropolitan Atlanta, 1970-1989, Journal of Medical Genetics 35: 482-90 (1998). Figure 8.20B Maternal age and incidence of Down syndrome
In some plants such as mosses and ferns, there is a multicellular stage in the life cycle that is haploid and a different stage that is diploid. What can you conclude from this?

A) The haploid cells must undergo twice as much mitosis in order to produce a diploid stage.
B) Haploid cells must undergo mitosis to produce a multicellular haploid stage.
C) Meiosis must happen over and over to produce as many haploid cells for a multicellular haploid plant.
D) Haploid cells must undergo meiosis to form gametes.

Question 75

After reading the paragraphs below, answer the questions that follow.
Mr. and Mrs. Smith have three sons in elementary school. Two of their children are progressing normally, but their youngest son, Charles, has been much slower than his siblings in developing speech and language skills. His parents are concerned that he has a learning disability and decide to investigate further. Since some learning disabilities can be genetically based, their pediatrician recommends a chromosomal analysis.
The results show that Charles has a trisomy of the sex chromosomes, diagnosed as XYY. A mistake during sperm formation resulted in an extra copy of the Y chromosome. The extra copy was passed on to Charles during fertilization. Most often, this chromosomal change causes no unusual physical features or medical problems, but those with trisomy of the sex chromosomes may have a higher-than-normal risk of delays in learning development.
The problem that occurred during meiosis in sperm formation was

A) nondisjunction involving a Y chromosome.
B) an inversion of the X chromosome, preventing the pairing of sex chromosomes.
C) failure of the second meiotic division to take place.
D) formation of diploid sperm.

Question 76

Use the figure below to answer the questions that follow.
Source: Adapted from C. A. Huether et al., Maternal age specific risk rate estimates for Down syndrome among live births in whites and other races from Ohio and Metropolitan Atlanta, 1970-1989, Journal of Medical Genetics 35: 482-90 (1998). Figure 8.20B Maternal age and incidence of Down syndrome
In comparing a frog cell in metaphase of mitosis with one in metaphase I of meiosis, how would tell you which was which?

A) In mitosis, the chromosomes would be unduplicated (single-stranded) and in meiosis, they would be double-stranded (made up of sister chromatids).
B) In meiosis, the chromosomes would be unduplicated (single-stranded) and in mitosis, they would be double-stranded (made up of sister chromatids).
C) Unlike meiosis, in mitosis each chromosome would be paired with its homolog.
D) Unlike mitosis, in meiosis each chromosome would be opposite its homolog.

Question 77

Use the figure below to answer the questions that follow.
Source: Adapted from C. A. Huether et al., Maternal age specific risk rate estimates for Down syndrome among live births in whites and other races from Ohio and Metropolitan Atlanta, 1970-1989, Journal of Medical Genetics 35: 482-90 (1998). Figure 8.20B Maternal age and incidence of Down syndrome
Which conclusion can best be drawn from this study?

A) Women of age 20 or younger never have a child with Down syndrome.
B) Women in this study who were 45 years old had three times the incidence of babies with Down syndrome as did 40-year-old women.
C) Many babies with Down syndrome die before birth.
D) For 40-year-old women around the world, ten births per thousand have Down syndrome.

Question 78

Oncologists (medical doctors who treat cancer patients) routinely take biopsies (samples) of tissue from patients to determine whether the tissue is cancerous or not. What would be the best technique to use to determine whether cells from the tissue sample are cancerous?

A) Count the number of chromosomes in the cells from the tissue sample and compare to the number of chromosomes in noncancerous cells from the patient.
B) Add cells from the tissue sample to a cell culture dish and compare their growth against a sample of noncancerous cells from the patient.
C) Measure the amount of DNA in G1 in the cells from the tissue sample and compare it to the amount of DNA in G2 in noncancerous cells from the patient.
D) Add cells from the tissue sample to a rat to see whether the rat develops cancer or not.

Question 79

A technique called flow cytometry is used by scientists and researchers to count or sort cells based on specific properties. By labeling cellular DNA with a fluorescent dye, flow cytometry can sort cells based on the amount of DNA present, thereby making it possible to distinguish between cells that are in different stages of the cell cycle. Flow cytometry is especially useful to the medical community because it can help with the diagnosis of certain types of cancers. Below is a typical set of data that you might obtain when running a flow cytometry experiment using a sample of healthy skin cells. Use this figure to help you answer the following questions. After reading the paragraph below, answer the questions that follow.
Which peak corresponds to cells in G1? In S phase? In G2?

A) A: G1; B: G2; C: S
B) A: G2; B: S; C: G1
C) A: S; B: G1; C: G2
D) A: G1; B: S; C: G2

Question 80

A technique called flow cytometry is used by scientists and researchers to count or sort cells based on specific properties. By labeling cellular DNA with a fluorescent dye, flow cytometry can sort cells based on the amount of DNA present, thereby making it possible to distinguish between cells that are in different stages of the cell cycle. Flow cytometry is especially useful to the medical community because it can help with the diagnosis of certain types of cancers. Below is a typical set of data that you might obtain when running a flow cytometry experiment using a sample of healthy skin cells. Use this figure to help you answer the following questions. After reading the paragraph below, answer the questions that follow.
In this sample of cells, what stage of the cell cycle are most of the cells in?

A) G1
B) S
C) G2
D) mitosis