Download Meiosis and Genetic Variation

Unit 4 REVIEW
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Sexual vs. Asexual Reproduction
Mendel’s Laws of Heredity
Patterns of Inheritance
Meiosis and Genetic Variation
Non-Mendelian Patterns of Inheritance
Reproduction/Cell Cycle/
Mitosis/Meiosis/Genetics
EQ: Sexual vs Asexual Reproduction?
SEXUAL REPRODUCTION - MEIOSIS
e.g.
*mammal reproduction,
*conjugation in bacteria
*any male + female sex cell fusion = syngamy
ASEXUAL REPRODUCTION - MITOSIS
e.g. Budding, Cuttings, binary fission,
regeneration, cloning, genetic engineering,
parthenogenesis (819)
Requires 2 parents or sex cells or gametes
(Sperm + egg) with haploid no. of chromosomes
unite to form a zygote with diploid no. of
chromosomes
Requires only 1 parent
Meiosis is the cell division that forms the sex cells
or gametes
Mitosis is the cell division involved in asexual
reproduction
Genetic diversity occurs as genes recombined
from 2 parents
No genetic diversity occurs….all offspring =
identical
EQ:
Advantages and Disadvantages of Asexual vs Sexual Reproduction?
Advantages of Sexual Reproduction
*Sexual reproduction  two organisms  formation of gamete cells. The gametes fuse together
causing genetic diversity
*This increases the chances of the organism evolving into a healthier and more adaptable species.
Genetic diversity ensures, there is a lesser chance of diseases and defects seen in parents being passed
on to their children.
Advantages of Asexual Reproduction
*One parent is needed to complete the process of asexual reproduction.
*In majority of the cases, one is sure an offspring will be produced.
*The gestation period or growth period is very short.
*The offspring has the same phenotype and genetic make up as the parent.
*As there is no genetic diversity the chance of mutation is very less.
Disadvantages of Sexual Reproduction
*Reproduction cannot occur until gametes from 2 parents fuse together.-time and energy
*Only half of the population that is, female species are capable of gestation.
*There is no guarantee that the nucleus of the male gamete will fuse with the female gamete after
mating. baby
*The time taken to produce an offspring by sexual reproduction is very long.
Disadvantages of Asexual Reproduction
*As the same genetic material from parent is directly passed on to the off spring, it causes all the
diseases and defects to be passed on to the offspring as well.
*As no recombination of genes occurs, chances of evolution are very low.
THE CELL CYCLE OCCURS IN EUKARYOTIC CELLS
EQ: What are the phases + events of the cell cycle?
* The CELL CYCLE = INTERPHASE + MITOSIS + CYTOKENESIS
•
•
•
•
•
G1 growth = Increase in size + makes new organelles
Interphase
S Phase = Synthesis of DNA = DNA Replication
G2 growth= More organelles produced= shortest phase
Mitosis /Meiosis=Nucleus Divides =P-M-A-T
Cell Division
Cytokenesis= Cytoplasm splits
* In Prokaryotes:
• No cell Cycle just Binary fission
EQ: How is cell cycle and cancer related?
• The cell is unable to pick up signals to
stop dividing due to a defective gene or
mutation.= gene mutation
• It continues to over-divide tumors Cancer.
• It is a problem with regulation of cell division
p289
p281
EQ: Mitosis vs Meiosis? Mitosis
p 326
1
*No. of Divisions
Meiosis
*# of Cells we begin and Begin with 1 cell
End with 2 cells
end with
Begin with 1 cell
End with 4 cells
Product
Genetic diversity
*No. of chromosomes in
beginning compared
with the number we end
with (Haploid +diploid)
2- Meiosis 1 and Meiosis 2
Body Cells/somatic cells
with same # chromosomes
we started with. Ex. brain,
nerve, any cell but sex cell
No crossing over of
chromosomes-no genetic
diversity
Sex cells/gametes
/sperm/egg/ovum-with ½ # of
chromosomes we started with
Diploid=same #
chromosomes as
Body Cells.We begin and
end with same #
chromosomes
2n2n
Haploid=1/2 we end with 1/2
of # chromosomes of body cells
Crossing over of chromosomes
occur in Meiosis 1metaphase=genetic diversity
2nn
EQ: Mitosis vs Meiosis p 326
MEIOSIS - PROPHASE 1 - Crossover + tetrads + chariasata
Tetrads
Crossover
segregation
EQ:2: What are the stages in Mitosis and Meiosis
Chart shows location of chromosomes during cell division)
Memory Chart of Phases Mitosis + Meisois: Location/chromosomes
P
M
A
T
Phase
prophase
metaphase
anaphase
telophase
Where are the Chromosomes
Prepare
Middle
Apart
Tails …
(May include cytokinesis)
Please Make All The ….. Classes Interesting
Cytokinesis
Interphase
Organism Clue
1.a gamete of a
housefly has 6
chromosomes
2. a human
muscle cell has
46 chromosomes
3. a leaf cell of
corn has 20
chromosomes
4. a haploid cell
of fruit fly has 4
chromosomes
5. a diploid duck
cell has
80chromosomes
EQ: HAPLOID vs DIPLOID CELLS
Body
cell
Gamete Haploid Diploid
cell
cell
Sperm
Egg
gamete gamete
p 327
N
2N
EQ: Results of Mitosis vs Meiosis / Haploid vs Diploid p 326
MITOSIS
MEIOSIS
STARTING
1 cell with X
chromosomes
ENDING
2 cells with
the same
number of x
chromosomes
started with
(1n)
EXAMPLE
1 cell with 10
chromosomes
2 cells each with 10
chromosomes each
=DIPLOID=BODY CELLS
1 cell with X
chromosomes
Ending with
HAPLOID=1/2
body cells.
4 cells each
with half of
original
number of X
chromosomes
(2n)
1 cell with 10
chromosomes
4 cells each with 5
chromosomes each
( ½ of 10 )
=HAPLOID =SEX CELLS,
GAMETES, EGG, SPERM
HAPLOID = 1/2 = (1n)
DIPLOID = HAPLOID x2 (2n)
HOMOLOGOUS CHROMOSOMES & CROSSING OVER
EQ: How does Crossing Over increase Genetic Variation?
Chromosomes that carry the same genes = homologous chromosomes
(don’t confuse compare w. homologous structures)
Homologous chromosomes crossover or trade pieces of genetic material before the
end of Metaphase I of Meiosis I …. This causes genetic variation.
This is associated with Mendel’s law of segregation + independent assortment.
WORD CLUSTERS:
MITOSIS:
• Produces Body cell or Somatic cell e.g. skin cell
• Starts with x number of chromosomes
• End with each cell same # chromosomes
• End product 2 Diploid Cells w/ the same # chromosomes
MEIOSIS:
• Produces the Gametes = sex cell, egg, or sperm
• Starts with x number of chromosomes
• End with each having ½ of chromosomes of original cell
• End product 4 Haploid Cells…w/Half the # chromosomes
• Crossover occurs  genetic variation
• Associated with Mendel laws of Heredity and Genetic
Inheritance
Vocabulary Words:
1. genetics + heredity p308
2. trait p309
3. genes and alleles p309-310
4. P1 generation; F1 generation (first filial);
F2 generation (second filial) p311/312/317
5. homozygous + heterozygous/example p314
6. dominant + recessive alleles/example p310
7. hybrid p309 /monohybrid cross/ex. & dihybrid
cross/ex p317
8. genotype + phenotype /example p315
9. multiple alleles/example p320
10. polygenic traits/example p320
11. gene linkage & sex linkage
p329
12. gene mapping
p329
EQ: Can
you describe the experiments done by Gregor Mendel? p308-309
• Which organisms he used + why (2 reasons) Which processes he do?
EQ: Which traits did Mendel observe in pea plants? p 310
• List 7 traits Mendel observed
EQ: Why did Mendel-Experiment w/Pea plants p 310
•Peas have a fast reproductive rate
•Male + Female parts of the flower were in the same flower.
EQ: Processes? = Cross and Self Pollination  fertilization
EQ: Traits Mendel Observed?
EQ: Name the main principles in Mendel’s Genetics
1.The Inheritance of Biological Characteristics is determined by
factors called Genes.
2. Law of Dominance - Each parent has an Allelle Pair (= a Gene) in
each cell for each trait studied (like Tt for height,) where one
allele for the trait is dominant over the other recessive allele..These
two alleles comprise the gene pair.
3. Law of Segregation - Alleles/letters for each gene pair segregate
into a gamete, thus each gamete only carries one member of the
gene pair. Happens in Meiosis.
4. Law of Independent Assortment –
Genes for different traits segregate +sort independently of each
other e.g. eye color separates independently of skin color.
Happens in Meiosis-Crossover-Metaphase I
EQ: Exceptions to Mendel’s Laws?
AKA = Complex Patterns of Heredity
1. Codominance (co- = together)
• eg AB Blood Type p 394 sickle cell p 324
2. Incomplete Dominance (~ Blending)
• eg Four O’Clock pink flowers (Rr) p 319
3. Multiple Alleles p 320
• eg Blood type allelles: A ,B , i p 320
4. Polygenic Traits
p 320
• eg skin color, height
5. Sex Linked Traits p 395
• eg color blindness, hemophilia
6. Non Disjunction-TrisonomyDown Syndrome
p 401
EQ: Exceptions to Mendel’s Laws?
AKA = Complex Patterns of Heredity
7. Genes and the Environment
EQ: How
can the environment effect Gene Expression?
p 321
• Phenotype of individuals is affected not only by
genetic factors but also by environmental factors
eg temperature, pH, chemicals.
• Phenotypes can be affected by mutations
EQ: Important SCIENTISTS in BIOLOGY?
Mendel, Gregor = GENETICS- +Laws of Genetics, genes,
inheritance
Hershey & Chase = DNA-Material in viruses is DNA not
protein.
Franklin, Rosalind = DNA is has a shape that appears double.
Watson & Crick = DNA-based on Franklin’s Xrays confirmed
that DNA has shape of a double helix.
Chargoff, Edwin = DNA-The bases AT are equal in numbers
just line C+G are equal in numbers.
Linnaeus, Carolus = Taxonomy/classification of living
organisms
Darwin, Charles = Theory of Evolution: natural selection 
adaptation  survival  reproduction > new species/speciation.
CHARTS/DIAGRAMS
* Punnett Squares
probability of genotypes and phenotypes in inheritance
-----------------------------------------------------------------* Karotype  chromosomes pairs in organisms p392
K showsAutosomes +Sex chromosomes
KCan show diseases of chromosomes like Downs
Syndome=chromosomes fail to separate=nondisjunction
-----------------------------------------------------------------* Pedigree Charts
* Dependent + Independent Variables
EQ: How are sex linked genes like hemophilia and color blindness
transmitted through the generation?
1. Hemophilia and color blindness are carried as a recessive gene on
X chromosome.
2. Because there are 2 XX in females one X dominates over the other
XH , the female has less chance of being color blind or having
hemophilia.
3. Men with XY chromomosme have a higher chance of being color
blind or having hemophilia
4. XHXh x XHY = Sex Linked color blindness or hemophilia
XH
XH
Xh
X HXH XHXh
Y
XHY
Xh Y
UNIT 4 VOCABULARY:
Topics: Reproduction, Cell Cycle, Cell Division, Genetics
4.1- asexual reproduction, gamete, sexual reproduction,
binary fission, genetic variation, budding, fertilization,
vegetative propagation, cancer, carcinogen, cell cycle,
chromosomes, mitosis, mutation
4.2- allele & genes, genetic cross, gamete, phenotype, genotype,
dominant, recessive, gamete, Punnett square,
independent assortment, segregation, homozygous, heterozygous,
Mendel, heredity, P generation, F1 Generation (first filial),
F2 generation (second filial) p 311-312/317
4.3- diploid, haploid, homologous, meiosis, crossing-over,
codominance, karyotype, incomplete dominance, polygenic traits,
genetic disorder, pedigree, sex-linked, multiple allele,
gene mapping
Learning Objectives - Students will be able to:
4-1: Identify relationships between cell structure and function. (SC.912.L.14.3)
4-2: Identify and describe the stages of the cell cycle. (SC.912.L.16.14)
4-3: Model the movement of chromosomes during mitosis. (SC.912.L16.14)
4-4: Explain the role of mitosis in the formation of new cells. (SC.912.L.16.14)
4-5: Relate the role of enzymes to the events that regulate the cell cycle. (SC.912.L.16.14,
SC.912.L.18.11)
4-6: Distinguish between the events of the normal cell cycle and those of uncontrolled cell
growth. (SC.912.L.16.8)
4-7: Analyze the relationship between mutation, uncontrolled cell growth, and cancer.
(SC.912.L.16.8)
4-8: Identify the importance of reproduction to living things. (SC.912.L.16.17)
4-9: Define asexual and sexual reproduction. (SC.912.L.16.17)
4-10: Identify that offspring produced by asexual reproduction are genetic copies of the
parent. (SC.912.L.16.14, SC.912.L.16.17)
4-11: Relate the process of mitosis to different types of asexual reproduction.
(SC.912.L.16.17, SC.912.L.16.15)
4-12: Explain that the offspring of sexual reproduction contain genetic information from
two parents. (SC.912.L.16.17)
4-13: Relate the process of sexual reproduction to genetic variation. (SC.912.L.16.17)
4-14: Compare advantages and disadvantages of asexual and sexual reproduction.
(SC.912.L.16.17)
4-15: Describe how Mendel conducted his experiments to study patterns of inheritance in
pea plants. (SC.912.L.16.1, SC.912.N.3.3)
Learning Objectives (cont.) - Students will be able to:
4-16: Explain that genes exist in alternative forms called alleles. (SC.912.L.16.1)
4-17: Contrast the inheritance patterns of dominant and recessive alleles. (SC.912.L.16.1)
4-18: Calculate ratios to explain experimental data related to heredity. (SC.912.L.16.1,
SC.912.L.16.2, SC.912.N.1.1)
4-19: Explain Mendel’s laws of segregation and independent assortment and relate them to
his experiments. (SC.912.L.16.1, SC.912.N.1.6,SC.912.N.3.3)
4-20: Differentiate between the genotype and phenotype of an organism. (SC.912.L.16.1,
SC.912.L.16.2)
4-21: Predict the results of a genetic cross using Punnett squares. (SC.912.N.16.1,
SC.912.L.16.2, SC.912.N.3.5)
4-22: Differentiate between haploid and diploid cells. (SC.912.L.16.16)
4-23: Analyze how gamete formation and fertilization maintain chromosome number within
a species. (SC.912.L.16.16)
4-24: Summarize the events that occur during meiosis. (SC.912.L.16.16)
4-25: Describe the processes of independent assortment and crossing over during meiosis.
(SC.912.L.15.15, SC.912.L.16.16)
4-26: Relate the behavior of homologous chromosomes during meiosis to Mendel’s laws of
heredity. (SC.912.L.15.15, SC.912.L.16.1, SC.912.L.16.16, SC.912.L.16.17)
4-27: Model how meiosis results in the formation of haploid gametes. (SC.912.L.16.16)
4-28: Explain how meiosis contributes to genetic variation within a species. (SC.912.L.15.15,
SC.912.L.16.17)
4-29: Compare and contrast mitosis and meiosis. (SC.912.L.16.17)
4-30: Identify observable dominant and recessive traits in humans. (SC.912.L.16.2)
Learning Objectives (cont.) - Students will be able to:
4-31: Interpret a pedigree to determine patterns of inheritance in families. (SC.912.L.16.2,
SC.912.N.1.6, SC.912.N.4.1)
4-32: Predict the pattern of inheritance of a simple dominant trait. (SC.912.L.16.1,
SC.912.L.16.2)
4-33: Explain how genetic disorders can be caused by inherited recessive alleles.
(SC.912.L.14.6, SC.912.L.16.2)
4-34: Analyze how incomplete dominance and codominance influence patterns of heredity.
(SC.912.L.16.2)
4-35: Explain how multiple alleles for a gene result in multiple phenotypes in organisms.
(SC.912.L.16.2)
4-36: Investigate how polygenic inheritance of a trait results in multiple phenotypes.
(SC.912.L.16.2)
4-37: Provide examples of how environmental factors influence patterns of heredity.
(SC.912.L.14.6, SC.912.L.16.2)
4-38: Trace the pattern of inheritance of a sex-linked trait. (SC.912.L.16.2)
4-39: Create a pedigree using family data to determine the inheritance pattern of a trait.
(SC.912.L.16.1, SC.912.L.16.2, SC.912.N.1.1)
EOC PRACTICE UNIT 4
pp1
1. What advantage do sexually reproducing organisms have over asexually reproducing organisms?
A. genetic variation
B. genetic stability
Slide 1+2
C. increased fertilization rate
D. increased reproductive rate
2. Which term best describes the type of cell division in which parent cells produce daughter cells with
the same number of chromosomes as the parent cells?
Slide 6/p 326
A. mitosis
B. meiosis
C. spermatogenesis
D. oogenesis
3. What is the primary cause of variation in the offspring of sexually reproducing organisms? Slide 1+2+7
A. cytoplasmic division B. environmental changes C . Mutation
D. recombination of alleles
4. A plant nursery only grew one type of tomato plant. All of their tomato plants died from the same
disease. What was most likely true of the tomato plant population?
Slide 1+2/p 277
A. They had a lot of resistance to disease.
B. They had a few plants that were resistant to the disease.
C. They had too much variation in their genes.
D. They had little variation in their genes.
5. How are sexual reproduction and asexual reproduction different from each other? Slide 1+2/p 277
A. sexual reproduction requires two parents and asexual reproduction requires only one parent
B. asexual reproduction requires two parents and sexual reproduction requires only one parent
C. mutation rates are lower in sexual reproduction than in asexual reproduction
D. asexual reproduction occurs only in multicellular organisms
6. Which description best identifies characteristics of asexual reproduction? Slide 1+2/p 277
A. one parent, union of gametes, offspring genetically identical to parent
B. one parent, no union of gametes, offspring genetically identical to the parent
C. two parents, union of gametes, offspring similar to but not genetically identical to parents
D. two parents, no union of gametes, offspring genetically identical to the parents
EOC PRACTICE UNIT 4
p2
7. A clone is the product of _____.
p277
A. asexual reproduction
B. sexual reproduction
D. meiosis
E. A and C
C. mitosis
F. B and D
8. A single-celled eukaryotic amoeba is dividing into 2 cells. Each new cell becomes an individual
organism. This is
A. budding B. asexual reproduction C. sexual reproduction D. fragmentation E. binary fission
9. Sexual and asexual reproduction are alike in that _____ Slide 1+2/PP277
A. they both involve two parents
B. they both require meiosis to complete the reproductive cycle
C. they can both occur in multicellular organisms
D. they both give rise to genetically distinct offspring
10. Sexual reproduction favors Slide 1+2/PP277
A. genetic stability
B. highly successful species
D. beneficial recombination
E. genetic diversity
11. Which of the following is not a form of asexual reproduction? Slide 2
A. fragmentation B. budding
C. parthenogenesis
D. syngamy
C. stable populations
E. binary fission
12. Which process is an example of asexual reproduction? Slide 2/pp277
A. An amoeba divides in half to form two amoebas.
B. A bee transfers pollen from one flower to another.
C. Female fish deposits eggs on a rock, then a male fish releases sperm on them.
D. Earthworms exchange sperm
EOC PRACTICE UNIT 4
p3
13. Mitosis and meiosis are processes involved in cellular reproduction. Which of the following
describes and event that results from mitosis but NOT meiosis?
p326 Slide 7
A. two stages of cell division
B. replication of cellular genetic material
C. daughter cells that are identical to the parent cell
D. four daughter cells that are produced from each parent cell.
14.Which of the following phrases best describes cancer?
p289
A. absence of cyclins in the DNA
B. multiple gene mutations on a chromosome of DNA
C. uncontrolled cell growth caused by mutations in genes that control the cell cycle
D. presence of genetic defects caused by hereditary disorder
15. Which process is correctly matched with the phase in which it occurs?
A. G1 phase, DNA replication
B. G2 phase, organelles copied
C. S phase, cell division
D. M phase, cell growth
p281
16. Which of the following represents the phases of mitosis in their proper sequence?
A. prophase, metaphase, anaphase, telophase
B. interphase, prophase, metaphase, anaphase, telophase
C. interphase, prophase, metaphase, telophase
D. prophase, anaphase, metaphase, telophase
Slide 6+8
EOC PRACTICE UNIT 4
p4
17. The diagram below shows the phases of Mitosis. Which diagram represents the anaphase?
A. 1
B. 2
C. 4
D. 5
Slide 5/p 282
18. What is the function of the structure labeled A in the drawing above
A. carry genetic information
B .hold chromatids together
C. anchor the spindle fibers
D. pull chromatids apart
p 282
19. What is the structure labeled B in the drawing?
p282
A. chromatids
B. spindle fibers
C. centrioles
D. centromeres
20. How many chromosomes would there be in each newly formed nucleus in a human cell at the end of
mitosis?
A. 12 B. 23
C. 46
D.92
Slide 5
21.During which phase of meiosis do homologous chromosomes align as tetrads in the middle of the
spindle?
p326/Slide7
A. prophase B. cytokinesis C. metaphase D. interphase
22.What term is used to describe pairs of chromosomes for the same traits?
A. homologous
B. homozygous
C. heterozygous
D.sex
p 323
EOC PRACTICE UNIT 4
p5
23. When mutations cause a failure in the regulation of cell growth and development, what condition
might occur? A. normal mitosis
B. cell plates form
C. cancer
D. meiosis p289
24. Mitosis, a stage in the cell cycle, is important for what reason?
p281
A. reduction of the cell’s chromosome number
B. removal of diseased cells
C. growth and repair of an organism
D. division of the cytoplasm
25. Which description best fits the activity of a cell during interphase? 281
A. the cell grows and chromosomes replicate
B. the cell differentiates to have a new function
C. cell splits in two, but with half the normal of chromosomes
D. the cell splits in two
26. If a gamete of an organism has 10 chromosomes; how many chromosomes would be in each of its
normal body cells?
A. 5
B. 10 C. 15 D. 20
Slide 5
27. A cell with 20 chromosomes undergoes mitosis, how many chromosomes will each of the 2 new cells
have?
A. 10
B. 20
C. 30
D. 40
28. A cloned plant has a diploid chromosome number of 12. What is the diploid chromosome number of
the plant cell that was used to produce the cloned plant?
Slide 5
A. 6
B. 12
C. 18
D. 24
29 . Which statement concerning both mitosis and meiosis is correct?
Slide 5 + 6
(A) meiosis produces 4 haploid cells while mitosis produces 2 diploid cells
(B) meiosis produces 4 diploid cells while mitosis produces 2 haploid cells.
(C) meiosis maintains the ploidy level, while mitosis reduces it
(D) prophase I of mitosis results in the formation of a tetrad but not in prophase I of meiosis
30. If gametes have 8 chromosomes resulting from meiosis how many chromosomes will the body cell
have
A. 4
B. 8
C. 16
D. 2
E. 1
Slide 5
EOC PRACTICE UNIT 4
p5
31. Which of the following phases of mitosis is represented by the diagram below?
A. prophase B. metaphase C. anaphase D. telophase
SL.6+8
32. The reduction of the chromosome number during meiosis is most important for -----A. keeping the amount of DNA in the cell at a minimum level
B. preventing the nucleus from becoming larger with each cell division
C. maintaining the chromosome number during sexual reproduction
D. allowing the growth of the cell without increasing the DNA content
33. Which of the following are mismatched
Slide 5 /326
A) haploid-n
B) somatic cells-2n
C) zygote-n
D) sperm cell-n
Sl.6/326
E) gamete-n
34. If a cell with 32 chromosomes divides by meiosis, how many chromosomes will each nucleus contain
at telophase 2 ? (Assume cytokinesis has occurred.)
A) 64
B) 48
C) 32
D) 16
E) 8
Slide 5/ 326
EOC PRACTICE UNIT 4
35. Cytokinesis refers to------A. division of the entire cell
C. division of the cytoplasm
36. Germ-line cells are
A. produce gametes
p6
p281
B. division of the nucleus
D. reduction in the number of chromosomes
Sl.5
B. are haploid C. usually undergo mitosis
D. are special somatic cells
37.If a zygote has 4 chromosomes, the somatic cells formed from it have ----- chromosomes.
A. 4
B. 8
C. 2
D. 1
E. 16 Slide 2
38. Unlike gametes, body cells are called
A. somatic
B. haploid
C. semantic
D. synergic
E. sematic
Slide 5
39. If a somatic human cell were just about to divide, how many chromatids would it have? Slide 5/ 326
A) 92
B) 46
C) 23
D) 0
40. The ovum of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic cells of
a rabbit?
A. 11
B. 22
C. 44
D. 88
Slide 5/326
41. In a diploid cell containing 10 chromosomes, meiosis results in the daughter cells containing ----chromosomes.
A. 5
B) 10
C) 20
D) 40
Slide 5/326
42. DNA replication occurs in -----pp281
A) prophase of both mitosis and meiosis
C) the G1 phase of interphase in reproductive cells only
B) the S phase of interphase
D) metaphase of meiosis only
EOC PRACTICE UNIT 4
p7
43. How many pairs of autosomes do humans have? A) 23
B) 22
C) 2
D) 1
Pp393/Slide 19
44. Meiosis takes place in which of the following organs?
(A) Testes (B) Lungs (C) Heart (D) Stomach (E) Skin
45. If 2n = 8, for a particular cell, then the chromosome number in egg cell after meiosis would be
(A) 12
(B) 10
(C) 8
(D) 4
46. Crossing over occurs during which phase of meiosis? pp324
(1) Prophase I (2) Metaphase I (3) Metaphase II
(4) Anaphase I
(5) Telophase II
47. Which one of the following is not a function of meiosis in humans? pp326
A .production of eggs B. production of sperm C. decreasing the number of chromosomes
D.multiplication of body cells
48. Crossing over ----- .
pp324
A) is the exchange of genetic material between non-homologous chromosomes.
B) occurs during prophase II
C) produces a tetrad that contains one or more chiasmata.
D) none of the above
49.Which genetic abnormality can be identified through a karotype chart
pp401/Slide 19
A. point mutation
B. recessive allele
C. extra chromosome + trisomy D. sex-linked allele
50. In pea plants, tall plants are dominant to short plants. If two heterozygous tall plants are crossed,
what percent of the offspring will probably be short? pp316 A. 50%
B. 25% C. 0% D. 75%
51.Which is responsible for most genotypic and phenotypic variation among humans? Slide 1+2
A. Meiosis
B.budding
C. mitosis
D. regeneration
EOC PRACTICE UNIT 4
p8
52. In pea plants, green is a recessive trait. A green pea plant would have:
A. two recessive allele
C. one dominant allele and one recessive allele
pp310
B. two dominant allele
D. not enough information to be determined
53. In the Punnett square shown in Figure-3, which of the following is true about the offspring
resulting from the cross? T=tall and t=short pp314
A. About half are expected to be short.
T t
B. All are expected to be short.
C. About three fourths are expected to be tall.
T TT Tt
D. All are expected to be tall.
t Tt
tt
54. Which of the following crosses does not follow Mendel’s law of segregation? pp314
A. Two tall pea plants (Tt x Tt) are expected to produce some tall offspring plants.
B. Two tall pea plants (Tt x Tt) are expected to produce some short offspring plants.
C. A tall pea plant and a short pea plant (Tt x tt) are expected to produce all tall offspring plants.
D. A tall pea plant and a short pea plant (TT x tt) are expected to produce all tall offspring plants.
51. Some flowers show incomplete dominance. If RR = white and R′R′ = red, which phenotypic ratio
would be expected in the offspring of two pink flowers? pp319
A. 1 red : 2 pink : 1 white
B. 0 red : 4 pink : 0 white
C. 3 red : 0 pink : 1 white
D. 4 red : 0 pink : 0 white
56. What is the primary cause of variation in the offspring of sexually reproducing organisms? Slide 1-2
A. cytoplasmic division
B. environmental changes
C. mutation
D. recombination of alleles
EOC PRACTICE UNIT 4
p9
57. Most sex-linked, recessive traits–including hemophilia and color blindness–appear in males. This
phenomenon is best explained by which statement?
A . Males have an X chromosome with dominant genes.
B . Most of the genes on the X and Y chromosomes of males are recessive.
C. In males, the recessive sex-linked genes appear only on the Y chromosome.
D. In males, the Y chromosome lacks the genes needed to mask the recessive genes on the X
chromosome.
58. The sex chromosomes of normal females are: pp 393
( A.) X and Y
(B.) Y and Y
(C.) X and X
(D) none of the above
59. A karyotype is a: pp401-402
A) general term for any type of chromosome
B) type of abnormal chromosome that is associated with Down's syndrome
C) picture of an individual's chromosomes arranged in a standardized way
D)A diagram of inheritance of traits
60. Normal humans have ----- pairs of autosomes and ------ pair(s) of sex chromosomes pp393
A. 23 and 23 B. 23 and 2 C.46 and 1
D. 22 and 1