49) 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.
50) 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.
51) Which of the following statements about nondisjunction is false?
A) Nondisjunction in meiosis can affect autosomes and sex chromosomes.
B) In mammals, extra copies of the Y chromosome are typically inactivated.
C) In general, a single Y chromosome is enough to produce “maleness.”
D) Women with a single X chromosome have Turner syndrome and are sterile.
52) Which of the following types of organisms commonly demonstrates polyploidy?
A) mammals
B) reptiles
C) flowering plants
D) fish
53) How many generations does it take to develop a new plant species by polyploidy?
A) 1
B) 2
C) 10
D) about 20
54) Which of the following variations of the sentence “Where is the cat?” is most like a
chromosomal deletion?
A) Where is cat?
B) Where is the the cat?
C) Where the is cat?
D) Where is cat the the cat?
55) 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.
56) 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.
57) 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. 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.
58) 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.
59) A cell is initially diploid, but it has a unique cell cycle in that this cell goes through two S
phases instead of one. What would the remainder of its cell cycle consist of if this cell is to
produce four identical diploid daughter cells at the end of its cell cycle?
A) two rounds of mitosis and one round of cytokinesis
B) one round of mitosis and one round of cytokinesis
C) one round of mitosis and two rounds of cytokinesis
D) two rounds of mitosis and two rounds of cytokinesis
60) 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
61) 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
62) You have two flasks (labeled A and 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?
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.
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.
63) Your friend is working in a lab whose members are supposed to be culturing (growing)
animal cells in petri dishes. They keep complaining to you, however, that no matter what they
do, they can’t get their cells to grow. Which of the following is not a possible explanation for
why the cells are not growing?
A) The cells need to be given the correct growth factors in order to grow.
B) The cells are too dense and thus need to be diluted in order to grow.
C) The cells are either mature human nerve or muscle cells, which do not divide and grow.
D) The cells are on petri dishes but should be floating in liquid media in order for them to grow.
64) When observing a chicken skin cell in G2 under a microscope, you count 156 total
chromatids. How many chromosomes does a male chicken have in its sperm cells?
A) 312
B) 156
C) 78
D) 39
65) 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.
66) 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
67) 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.
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 an above-average
intelligence. 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
69) 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
experiment to do 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.
8.2 Art Questions
1) What event will immediately follow the event shown in this image?
A) The cell will divide into two animal cells.
B) The cell will divide into two plant cells.
C) The cell will divide into four animal cells.
D) The cell will divide into four plant cells.
2) 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
3) If these four cells 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
8.3 Scenario Questions
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, which
is caused by nondisjunction in the formation of the father’s sperm. The nondisjunction 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 do have a higher than normal
risk of delays in learning development.
1) During which stage of meiosis could this nondisjunction have occurred?
A) telophase I
B) prophase I
C) anaphase II
D) telophase II
2) If Charles gets married and starts a family, which of the following chromosomal abnormalities
has an increased chance of occurring in his children?
A) YO
B) YY
C) XO
D) XXY
After reading the paragraphs below, answer the questions that follow.
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.
3) Which peak represents cells that contain the most DNA?
A) A
B) B
C) C
D) It cannot be determined from this figure.
4) 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
5) 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
6) 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