001-028 U2-AK BIO11TR
嚜澤nswer Key
Unit 2 Genetic Processes
13. Daughter cells formed during cell division are
genetically identical to the parent cell.
Unit Preparation Questions
(Assessing Readiness)
14. In plant cells, a cell plate is formed during cytokinesis
and divides the cytoplasm into two. Animal cells are
divided by a contractile ring rather than a cell plate.
(Student textbook pages 154每7)
1. b
2. In both animal and plant cells: A每cell membrane
B每cytosol
C每mitochondrion
E每endoplasmic reticulum (smooth and rough)
G每Golgi apparatus
H每nucleus (or nuclear envelope)
L每nucleus (or nuclear envelope)
In plant cell only: I每central vacuole
J每cell wall (or membrane)
K每chloroplast
In animal cell only: D每ribosomes
F每vesicle
3. For efficient movement of materials the ratio of a cell*s
surface area to volume must stay within a range that
permits diffusion to all parts of the cell within a short
amount of time (to support the metabolic activity of
the cell).
4. d
5. Nucleus (contains) ↙ chromosomes (composed of) ↙
DNA (which is made up of) ↙ genes (which code for)
↙ proteins
6. d
7. Students should draw a double helix and label any
small piece as a gene.
8. a
9. c
10. Mitosis involves the division of the nuclear material in
the nucleus and cytokinesis is the process that divides
the cytoplasm (including all organelles).
11. During cell division, DNA is tightly coiled in
chromosomes and looks ※bunched.§ The rest of the
time, the DNA looks more like long, loose threads.
12. A每centrosome
B每chromosomes
C每spindle fibres
D每centromere
15. A每interphase
B每growth and preparation (G1)
C每DNA replication
D每growth and preparation (G2)
E每mitosis
F每cytokinesis
16. Any two of: the DNA may be damaged; DNA
replication may not have occurred; there were not
enough nutrients to support cell growth; no additional
cells of that type are needed; cell death may have
been signalled
17. Sample answer: Skin cells have a short life span〞skin
is easily damaged and must often be replaced. Nerve
cells have a long life span〞these internal cells are
rarely damaged and, once an organism is full size, there
is no need to divide for growth.
18. Cancer results from uncontrolled cell reproduction and
the lack of cell death triggered by errors in DNA.
19. Sample answer: The digestive system is made of organs
including the stomach and small intestine, and tissues
like muscle (which move food along) or epithelium
(which line the tract). Muscle tissue is made of muscle
cells and epithelial tissue is made of epithelial cells.
Diagrams could look like the one that accompanies
question 38 on student textbook page 437.
20. Cell differentiation describes the process by which
a cell specializes to perform a specific function.
Because they perform different jobs, muscle cells
look very different from skin cells and nerve cells, for
example. If cells didn*t differentiate, they would all be
generalists〞they would be able to do all functions,
but not very well.
21. Stem cells can specialize to become many types of cell.
Other types of adult cells can only divide to produce
cells identical to themselves.
Biology 11 Answer Key Unit 2 ? MHR TR
1
Chapter 4 Cell Division and
Reproduction
Learning Check Questions
(Student textbook page 164)
1. Interphase, mitosis, and cytokinesis
2. Interphase
3. At prophase, the cell*s chromatin condenses into
chromosomes. Each chromosome exists as two copies
of one chromosome, joined at a centromere.
4. When mitosis is inhibited, healing times increase.
5. Interphase would differ in length between cell types
because different cells have different functions that are
carried out during interphase. Mitosis and cytokinesis
are processes that would likely be consistent for all
cell types.
6. The daughter cells would either have twice as much
DNA as a healthy cell, or no DNA. Neither cell would
be viable. One would lack genetic material and the
other would have too much to be able to survive.
(Student textbook page 172)
7. A gamete is a haploid sex cell and a zygote is a
diploid cell.
8. Thirty-nine chromosomes; gametes are haploid,
meaning they contain half the number of
chromosomes that are in a diploid cell
9. See Figure 4.14 on student textbook page 172 for
illustration; each homologous chromosome still
consists of two sister chromatids. In mitosis, the sister
chromatids are separated during anaphase.
10. The gametes would have 46 chromosomes (23 pairs).
After fertilization, the zygote would have
92 chromosomes (four sets of 23).
11. The phases in meiosis II (metaphase II, anaphase II,
and telophase II) are most like the phases of mitosis
because, during these stages, the chromosomes
align on the equator of the cell, sister chromatids are
separated, and a new nucleus forms for each new cell.
12. During anaphase I and anaphase II, because this
is when the homologous chromosomes and sister
chromatids, are each separated
(Student textbook page 176)
13. The outcome of mitosis is genetically identical
offspring, whereas the outcome of meiosis is one
(or four) haploid cells with a genetically diverse
2
MHR TR ? Biology 11 Answer Key Unit 2
representation of the parent cell. This leads to
genetically unique offspring.
14. 27 = 128 different gametes
15. Students may redraw the figure showing chromosomes
that are mixes of pieces of blue and yellow.
16. Because of independent assortment and crossing over,
all children will have some genetic material from each
of their ancestors.
17. Alleles that are found close together on the same
chromosome will be inherited together more often
than those that are either far apart on a chromosome or
on different chromosomes.
18. The ideal donor is an identical twin, because they are
genetically identical.
(Student textbook page 185)
19. Artificial insemination allows wider access to highquality male donors.
20. Both of these processes allow for the introduction of
genetic variation from different parts of the world.
21. A vector carries the gene of interest into the
foreign cell.
22. They are much less expensive to produce in
large quantities.
23. A company may use embryo transfer so that they can
choose desirable characteristics for their animals,
and shipping embryos is much easier than shipping
animals. This also allows offspring to grow up in their
permanent environment.
24. Sample answer: The bacteria do or do not do something
to the protein that would normally occur in the
human tissue.
Caption Questions
Figure 4.4 (Student textbook page 162): Unequal
distribution in anaphase could lead to unequal distribution
of chromosomes between new cells. This would lead to
chromosomal disorders or cells that were not viable.
Figure 4.10 (Student textbook page 167): They are
homologous because they are two X chromosomes that are
the same length and carry genes for the same traits at the
same location.
Figure 4.12 (Student textbook page 169):
six chromosomes
Figure 4.13 (Student textbook page 171): Meiosis I would
produce cloned cells, resulting in less genetic diversity
introduced into the cell and the organism.
Figure 4.25 (Student textbook page 184): The vector DNA
contains DNA only from one source, while recombinant
DNA contains the vector DNA and the DNA being cloned.
Figure 4.26 (Student textbook page 185): The nucleus is
removed from the egg cell so that it will only contain the
nucleus with the desired (inserted) genes.
Figure 4.28 (Student textbook page 187): Reduced crop
loss due to disease will result in larger harvests. This saves
the farmer money and allows lower prices.
Figure 4.29 (Student textbook page 188): Students may
suggest that animal genes should not be manipulated for
human benefit, period; that the welfare of the animals
should be considered; or that any method available
should be used to alleviate human suffering. Any answer
supported by an argument is acceptable.
Section 4.1 Review Questions
(Student textbook page 168)
1. All living things are composed of one of more cells.
Cells are the smallest units of living organisms. New
cells come only from pre-existing cells, by cell division.
2. Sample answer: Skin cells undergo mitosis more
frequently than nerve cells do. The skin cells will divide
and repair the cut before the nerve cells are replaced.
3. In a child, because a child is growing in addition to
repairing and replacing tissue
4. G1 is a period of rapid growth and normal cell duties.
S is a period of DNA replication so that each cell
produced receives a full set of DNA. During G2, cells
prepare for division; organelles are made so that new
cells have full complement of information.
5. a. anaphase
b. prophase
c. telophase
6. Sketches should look like Figure 4.4.
7. Sample answer: DNA replicates and I am connected to
my twin; we condense to make chromosomes, line up
along the equator, are pulled apart to opposite sides,
and are then surrounded by a new nuclear membrane.
We relax and get to work.
8. Mitosis duplicates and divides the nuclear material
and cytokinesis divides the cytoplasm, producing two
daughter cells.
9. Daughter cells are genetically identical to parent cells
(except in the case of a mutation).
that when cytokinesis occurred, there would be a
completely random division of the genetic material or
that cell division would stop.
11. The error most likely occurred during anaphase, when
the chromosomes are divided for the new daughter
cells. The centromere did not divide or spindle fibres
only formed from one centrosome, resulting in all of
the chromosomes moving to the same pole. When
cytokinesis occurred, all of the chromosomes were
on one side of the cell. The other daughter cell had
no chromosomes.
12. Students should sketch the basic structure of DNA,
indicating nucleotides and that a certain section of
the DNA contains a gene. Thin threadlike substances
should represent chromatin, and something resembling
the chromosome structure. Sketches should show
that DNA is a component of both chromatin and
chromosomes, such as in Figure 4.7 on student
textbook page 165.
13. Chromosome pairs are not necessarily identical (due
to copying errors, etc.) but the pairs are homologous,
meaning their genes are in corresponding locations but
may have different coding.
14. Diagrams should combine Figures 4.5 (on student
textbook page 163) and 4.9 (on student textbook
page 167).
15. Diagram should show an entire set of chromosomes,
with three that are identical in both size and banding.
16. The X and Y chromosomes determine the sex of the
individual; a female has two Xs and a male has one X
and one Y.
17. a. This is a karyotype, prepared by collecting a cell
sample that is treated to stop cell division during
metaphase of mitosis, then stained to produce a
banding pattern on the chromosomes that is clearly
visible under a microscope. Chromosomes are then
sorted and paired. The autosomes are numbered 1
through 22 and the sex chromosomes are labelled
as X or Y.
b. Male
c. Yes, this individual has the correct number of
chromosomes (23 pairs, 46 altogether).
18. By matching homologous chromosomes (which should
be the same size and pattern), the doctor would see
that one chromosome is shorter than it should be.
10. Since microtubules are responsible for the accurate
division of the chromosomes, it is likely that the
chromosomes would not move to the poles, and
Biology 11 Answer Key Unit 2 ? MHR TR
3
entanglement of chromatids during prophase 1 that
leads to pieces of chromosome changing places.
Section 4.2 Review Questions
(Student textbook page 181)
Both lead to variation by creating unique combinations
of chromosomes and genes in the sex cells. Sketch
should combine information from Figures 4.18 and 4.19
on student textbook page 175.
1. a. meiosis
b. fertilization
c. mitosis
2. a. 2n = 64
b. n = 32
c. 32
d. 64
12. Sketches should accurately represent the errors in
chromosome structure as shown in Table 4.1 on
student textbook page 177.
3. fertilization
4. Meiosis produces cells that:
? are genetically diverse; and
? contain half the number of chromosomes (are haploid)
5. a. Metaphase II
b. Sketches should show that the sister chromatids
separate and move to opposite poles of the cell.
c. Different colours illustrate that genetic material was
exchanged during crossing over.
d. 2n = 8
6. Meiosis takes place in the reproductive organs (ovaries
and testes).
7. Homologous pairs line up next to each other to make
a tetrad. This leads to chromosomes becoming tangled
(synapse) and DNA trading places. This leads to
increased variation in the daughter cells.
8. Mitosis and meiosis II are very similar in that the
chromosomes line up on the equator and are separated
during anaphase. The significant difference is that
mitosis separates the chromosomes of a diploid cell,
but in meiosis II the cell is haploid.
9. Sample answer:
Spermatogenesis
rQSPEVDFTNBMF
TFYDFMMT TQFSN
rDFMMTQSPEVDFE rQSPEVDFTIBQMPJE
rPDDVSTJO
HBNFUFTGSPN
UIFUFTUFT
EJQMPJEDFMMT
rTUBSUTXJUI
CZNFJPTJT
TQFSNBUPHPOJVN
rFWFODZUPQMBTNJD
EJWJTJPO
Oogenesis
rQSPEVDFTGFNBMF
TFYDFMMT FHHT
rDFMMBOEQPMBS
CPEJFTQSPEVDFE
rVOFWFODZUPQMBTNJD
EJWJTJPO
rTUBSUTXJUI
PPHPOJVN
rPDDVSTJO
UIFPWBSJFT
10. 25 = 32 distinct gametes
11. Independent assortment refers to the fact that the
orientation of each pair of chromosomes along the
equator is independent of the orientation of the
other pairs (ensuring a mix of maternal and paternal
DNA goes to each pole). Crossing over refers to the
4
MHR TR ? Biology 11 Answer Key Unit 2
13. Chromosomes do not separate evenly during nondisjunction. During anaphase II, a centrosome may
not divide, leading to sister chromatids both going to
the same pole. During anaphase I, a spindle fibre may
attach to both homologous chromosomes and pull
them to the same pole. This results in one cell having
one too many chromosomes (called trisomy) or one
too few chromosomes (called monosomy).
14. By looking at the homologous pairings in a karyotype,
a clinician can quickly see if one of the chromosomes
is missing its homologue (monosomy) or has two
homologues/three identical chromosomes (trisomy).
15. Invasive methods of prenatal genetic testing pose a
risk to the fetus. If there are no indications of genetic
abnormality, there is no reason to put the fetus at risk
of miscarriage (i.e., invasive methods can be avoided).
16. Students* arguments should be supported by
statements from either the textbook or individual
research. Students will likely find that it was difficult to
be entirely in favour of or against this type of testing,
illustrating the dilemmas faced by many.
Section 4.3 Review Questions
(Student textbook page 190)
1. Selective breeding. Farmers choose the best animals to
breed with each other by looking at the traits that they
considered favourable (for example, the fastest or those
which produced the most milk).
2. Ways to produce these traits should relate to finding
parent animals with the same traits. Students may
mention selective breeding or artificial insemination.
3. Answers should contain supporting information
such as:
In favour〞anything that makes us better should
be encouraged; taking the best characteristics and
allowing people to pick and choose their skills will
make us more productive
Opposing〞it is not right to interfere with nature;
everyone could end up being highly skilled in the same
areas and we wouldn*t have people who would want to
or be able to do other jobs
4. Both embryo transfer and IVF involve in vitro
fertilization of egg by sperm. In humans, there is
usually no genetic basis for choosing the egg and
sperm donor. Most human IVF procedures are
undertaken as a result of a fertility problem. Usually in
humans, the embryo is implanted into the female that
donated the egg, whereas in animals, the embryo is
usually implanted in an unrelated female
5. Vectors act as carriers of DNA that a scientist wants to
clone, enabling that DNA to be copied to a foreign cell.
This is important for applications such as gene therapy
and making insulin.
6. Gene cloning copies a segment of DNA, usually for the
purpose of protein production or study. Therapeutic
cloning produces genetically identical cells, usually for
medical treatments. Reproductive cloning produces
genetically identical individuals.
7. Flowcharts and diagrams should accurately represent
the process as shown in Figure 4.25 on student
textbook page 184.
8. Binary fission; some cells underwent conjugation or
had vectors inserted into them
9. Somatic cell nuclear transfer uses an egg cell (with
its nucleus removed) and the nucleus from a somatic
cell. The daughter cells are genetically identical to the
somatic cell.
10. Producing insulin through transgenic plants is
less expensive.
11. The animals produced through reproductive cloning
suffer from health problems and reduced lifespan, and
many are not even born alive.
12. He can choose to breed his schnauzer with another
prize-winning dog (selective breeding) or he could
clone it. Cloning would produce the most exact copy.
13. Stem cells are used in regenerative medicine because
they are undifferentiated. When they are placed into
a patient, they can be stimulated to differentiate and
replace the defective cells of the patient.
14. Students may choose examples such as transgenic
animals like goats which are designed to produce
medical protein products like HGH in their milk,
or pigs that can act as organ donors.
15. a. Sample answer: The Canadian government should
consider the benefits of the transgenic carrots
over regular carrots: are the worms and insects a
significant crop risk? Will it cause more economic
success? Where did the genes come from? Are the
genes naturally-occurring in the area? Will pesticide
eliminate desirable bugs as well? Might the pesticide
genes cross over to other plants? Are there any
possible health risks to those who eat the carrots?
b. Sample answer: The biggest advantage is that
crops will be larger and of a better quality. Other
advantages may be that fewer pesticides are needed,
and that pesticides are delivered at the site of
concern and in the smallest possible amounts,
reducing toxic runoff. Disadvantages might include
a higher seed cost, resulting in higher market prices
and fewer sales. The public may also be reluctant to
buy transgenic food.
c. Answers should show an understanding of the
arguments mentioned in the subsection entitled
※Regulating the Use of Transgenic Organisms§ on
student textbook page 188.
16. Students may agree or disagree. If they agree,
arguments might include that it will save lives (prevent
deadly allergic reactions). If they disagree, arguments
might include that there are more pressing issues
than creating a peanut that doesn*t cause an allergic
reaction, or that the causes of allergies are more
complex than a simple allergen每reaction relationship,
and that other solutions are possible.
Chapter 4 Review Questions
(Student textbook pages 195每7)
1. d
2. d
3. e
4. e
5. c
6. a
7. e
8. b
9. growth, repair, and maintenance
10. The bases in DNA connect to each other in a way
that looks like the rungs of a ladder. The sugar and
phosphate make the rails of the ladder, joining the
rungs. The comparison is limited because a real ladder
is flat but DNA is twisted in a helix.
Biology 11 Answer Key Unit 2 ? MHR TR
5
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