Exam 1 Q3 Review Sheet
Honors Biology
Exam 1Q3 will cover:
Chapter 8: ALL
MEIOSIS AND GENETIC DIVERSITY
½. Quiz 3 Q2 Review Sheet
1. Compare the chromosome number of a cell before going through meiosis and the cells
after meiosis. If a tetraploid cell goes through meiosis the four resulting cells will
be…diploid.
2. What are the reasons organisms perform meiotic cell division. In animals we said it is
to make the gametes, but in plants and fungus…
3. Why is meiotic cell division also called reduction division?
4. Compare gametogenesis, spermatogenesis, oogenesis and meiotic cell division. Where
does each of these occur?
5. Mitotic cell division is also known as the cell cycle, while meiotic cell division is not.
Explain.
6. Use the “finger method” of showing meiosis. Be sure to identify meiosis I and meiosis
II and the general purpose of each of these stages (What is being pulled apart in each?)
7. Explain why you are not surprised that meiotic cell division has mitotic cell division
built into it (meiotic division is just mitotic division with a few more levels of complexity
added on).
8. Why pair up the homologous chromosomes? Why not pair them up randomly or not
pair them up at all? Same for the sisters, why not just replicate the DNA in S and let the
sisters randomly move around not attached by a centromere?
9. For the “essay” question you will need to explain how gametes are made from a single
somatic diploid cell (meiotic cell division). You will be required to draw and label a cell
for each subphase (G1,S,G2,PI,MI,AI,TI/cytokinesis, PII, MII, AII, TII/cytokinesis).
Make sure you draw the final gametes. Do not leave them hanging in TII/cytokinesis.
Because meiosis II happens twice at the same time, you only need to draw it once and say
that is happens twice, once per daughter cell of meiosis I. Under each image should be a
set of bullets describing what is happening in that image. You need only label a structure
once. The starting cell will have a haploid number of 2 (n=2).
(The following terms should be included: haploid, diploid, synapsis, tetrad, homologous chromosomes,
crossing-over, centrosomes, mitotic spindle, kinetochores, motor proteins, centromere, microtubules,
metaphase plate, sister chromatids, chiasma, recombinant chromosome, meiosis I and associated subphases,
meiosis II and associated subphases, chromatin, nuclear envelope, tetrad, sister chromatids, daughter
chromosomes, MTOC, microtubules, spindle fibers, poles, cleavage furrow, centrioles, aster, ATP, plasma
membrane, DNA replication, centrosome replication)
33. What is meant by an evolutionary trade-off? Give examples.
34. Why go through all the trouble of reproducing sexually? Explain how influenza of
1918, HIV and Irish potato blight fit into this picture.
35. Explain why you are 1 in some ridiculous number of possible offspring that your
parents could have had.
36. Be able to calculate the number of possible gametes of any diploid organism
regardless of haploid number as well as the number of possible offspring between two
such organisms (this is excluding crossing over and mutation of course).
37. Explain in detail the four methods discussed that lead to genetic diversity in sexually
reproducing organisms. Which of these four is almost the sole means of genetic diversity
in asexual organisms. Which of these four is the creative process behind evolution in
terms of creating new genes resulting in new characteristics in organisms.
38. Describe precisely what alleles are. Give examples.
39. If I say that two genes are linked, what does that mean. How can genes be unlinked?
40. Explain in general how crossing over happens. What do the proteins/enzymes
involved in this process need to do?
41. Compare parental type chromosomes to recombinant chromosomes. How do
recombinant chromosomes form?
42. Describe how a human might end up with an abnormal number of chromosomes (We
discussed two general nondisjunctions. You should be able to draw these simple events).
43. Explain how we determine if a human whether born or unborn has an abnormal
number of chromosomes. How do we karyotype people? Why do we want to look at
chromosomes in metaphase as opposed to interphase or anaphase?
44. Describe how a centrifuge works.
45. What can a karyotype tell us?
46. Describe trisomy 21, trisomy 16, and the diseases resulting from nondisjunctions of
sex chromosomes.
47. Describe in detail how someone would end up with three number 21 chromosomes
starting from the somatic cells that will undergo meiotic cell division to conception of the
human with trisomy 21.
48. Describe the other mishaps that can happen during crossing over of meiosis like
deletions, etc…
49. Identify the three diseases caused by chromosomal deletions and describe each one.
50. What is so amazing about the dystrophin gene?
51. Explain why duplications are typically not as severe as deletions, and why
duplications might be very important in terms of evolution.
52. Explain why in order for the organisms to have any of these diseases like trisomy 21
or muscular dystrophy, the chromosomal changes must be in the gametes. For example, I
might end up with trisomy 21 in one of my cell in the retina of my eye. Does this have or
will it have anything to do with Down Syndrome?
53. In terms of heredity, explain why I would not be too worried about my future children
if I were to accidently step into the X-ray laser at the lab and it hit me in the chest.
54. In order for offspring to be affected, changes in the chromosomes must happen in the
gametes or the cell that will form the gametes. Any other changes in any other cells in
your body will do nothing to your offspring. Make sure you understand this.
55. Study the powerpoints. Everything you need to know should be in there.
I will put some awesome mitosis/meiosis videos up on the website under the misc.
section. Check them out…(look for today’s date next to them).