Meiosis

Concept: Meiosis Overview

5m

Concept: Prophase I and Crossing Over

4m

Concept: Metaphase I, Anaphase I, and Telophase I

4m

Concept: Meiosis II

3m

Concept: Nondisjunction and Independent Assortment

7m

Problem: Which phase of the cell cycle is lacking between the two meiotic divisions?

7m

Problem: A diploid organism has 28 chromosomes. How many chromosomes will the cell have after mitosis but before cytokinesis?

1m

Problem: A scientist observes cells undergoing meiosis. At the end of meiosis I, it is noted that the two resulting daughter cells are both haploid. This is because the cells that resulted from meiosis I are _________ but are composed of two sister chromatids that will be pulled apart during ___________, producing haploid gametes.

1m

Problem: Why do most genes sort independently?

1m

Related Topics

Meiosis Additional Practice Problems

A hybrid allotetraploid plant (4n=60) was backcrossed to one of the suspected parents (2n=30). WHen the F1 underwent meiosis, the prophase chromosome configuration (where you see synapsis/pairing of homlogs) was examined under a microscope. What would you expect the chromosome configuration to look like?

A. 45 singles

B. 15 pairs and 15 singles

C. 30 pairs and 15 singles

D. 60 singles

E. 30 pairs

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The red European squirrel has 12 pairs of large, long chromosomes. The grey squirrel has 20 pairs of smaller, shorter chromosomes. What do you expect to be the chromosome number in somatic tissued of a red/grey squirrel hybrid?

A. 16

B. 13

C. 20

D. 32

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In sexually reproducing organisms, meiosis generates haploid (1n) gamete cells  from diploid (2n) cells. The n represents the number of chromosomes in a cell's set of chromosomes. Haploid cells have one set of chromosomes, where diploid cells have two sets of chromosomes.

How does a zygote form from gametes?

A. Two haploid gametes combine to produce a diploid zygote that can develop into an embryo.

B. Each haploid gamete replicates its set of chromosomes to produce a diploid zygote.

C. A haploid zygote forms from the gamete with the strongest alleles and the other gametes die.

D. The four gametes fuse into a zygote with a twice as many sets of chromosomes as a diploid cell.

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A cell containing 24 chromosomes at the start of meiosis would at its completion produce cells containing:

A. 96 chromosomes

B. 24 chromosomes

C. 12 chromosomes

D. 48 chromosomes

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Physically, what are different alleles?

A. Different alleles are different DNA sequences found at the same locus on homologous chromosomes.

B. Different alleles are defferent DNA sequences found at the same locus on sister chromatids.

C. Different alleles are different particles found in gametes.

D. Different alleles are different phenotypes for a particular character.

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The figure below shows four cells (A-D) that are undergoing meiosis. Match each cell to the phase of meiosis that it is currently in.

A. Interphase

B. Prophase I

C. Metaphase I

D. Anaphase II

E. Metaphase II

F. Anaphase I

G. Telophase II

H. Telophase I

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You have isolated a single cell from a diploid organism. Which of the following would indicate that the cell was at metaphase of meiosis I and NOT metaphase of meiosis II?

A. All the chromosomes were composed of one chromatid.

B. It has a metaphase plate.

C. Homologous chromosomes were present.

D. All the chromosomes were composed of two chromatids.

E. There was only one copy of ech type of chromosome.

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The A and B genes are on nonhomologous chromosomes. A zygote is formed by the fusion of a sperm with genotype AB and an egg with the genotype ab. The zygote develops into a male. Which of the following are genotypes of sperm that could be produced by this male?

A. AB and ab only

B. AB, ab, Ab, and aB

C. only AB

D. only ab

E. aB and Ab only

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Would you expect to observe crossing over in the male 23rd pair of chromosomes? Explain.

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A crossover has occurred in the bivalent shown below:

What is the outcome of this single-crossover event? 

If a second crossover occurs somewhere between A and C, explain which two chromatids it would involve and where it occurs (i.e. between which two genes to produce the types of chromosomes shown here:

A. A B C, A b C, a B c, and a b c

B. A b c, A b c, a B C, and a B C

C. A B c, A b c, a B C, and a b C

D. A B C, A B C, a b c, and a b c

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Distinguish between interphase interkinesis. and cytokinesis. 

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What events that occur during prophase I have a major impact on the survival of the species?



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Where is the specific location in an animal where cells are undergoing Meiosis? In a Plant?

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Which cell shown here represents a diploid cell?

A. A only

B. B only

C. Both A and B

D. Neither A nor B

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At the end of meiosis, daughter cells are produced whose chromosomes are:

A. haploid

B. diploid

C. non-homologous

D. Both A and C

E. Both B and C

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Cell Cycle control 

Identify the three cell cycle check points and recognize the specific importance and role of each for the progression of the cell cycle. Compare and contrast the behavior of normal and cancer cells as it relates to cell density anchorage to surfaces, mortality versus indefinite reproduction, and cell cycle control.


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What process creates diploid cells from haploid cells?

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Explain the difference between homologues and sister chromatids.

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Compare and contrast Meiosis I with Meiosis II. Identify 2 similarities and 2 differences between Meiosis I and Meiosis II.

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A diploid organism has 14 chromosomes in its somatic cells. What is the total number of combinations of chromosomes that the organism can produce in its gametes, assuming no cross occur? ____. (enter numeric answer below)


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Imagine that the cell in the figure below is from a bird known as a blue-footed booby.

a. Is this cell undergoing mitosis, meiosis I, or meiosis II? HOW DID YOU DECIDE?

b. What is the diploid number of the organism from which this cell arose?

c. Name the structures being pulled apart by the spindle fibers.

d. Has crossing over occurred in this cell? If so, for which alleles?

e. What combination of alleles (i.e., what  genotype) will be found in each of the daughter cells that immediately result from the completion of the cell-division stage shown above?

f. What is the genotype of the individual (or the diploid cell) that gave rise to the cell above?

g. How many genetically distinct or different gametes (with respect to the genes and alleles shown) can an individual with this diploid genotype produce? Please write the genotypes for all possible gametes that this individual could produce.

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Assume that the cell illustrated in the figure below is from a species of crab.

a. Is this cell undergoing mitosis, meiosis I, or meiosis II? HOW DID YOU DECIDE?

b. What is the haploid number of this species (i.e., in a gamete produced by an organism of this species)? What is the species’ diploid number?

c. Has any crossing-over occurred prior to this stage? If so, for which allele(s)?

d. Will the daughter cells from this division be haploid or diploid?

e. How many chromatids would be present in a muscle cell from this crab in the G2 phase of its mitotic cell cycle?

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Assume that the cell in the figure below is from a crayfish testis and is about to undergo spermatogenesis (gamete production by meiosis). The letters represent alleles at particular gene positions (e.g., A and a alleles for one gene; B and b alleles for another gene, etc.) on each
chromosome.

a. Have the chromosomes replicated yet? Is the cell shown haploid or diploid? HOW DID YOU DECIDE? What is the haploid number of a sperm cell from this the crayfish? What is the diploid number of this crayfish’s somatic cells?

b. How many chromosomes might you observe in a muscle cell at G0 from this crayfish?

c. What are all the possible combinations of alleles that could be found in a gamete produced by the cell in the figure above?

d. Which of Mendel's laws tells us that a gamete containing a chromosome with the "A" allele will not necessarily contain a chromosome with a "B" allele?

e. Which of Mendel's laws tells us that a gamete cannot contain both an "A" allele and an "a" allele?

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The orignal parent cell had a single pair of homologous chromosomes. Which drawing could possibly be metaphase II if the parent cell underwent meiosis?

a. I

b. II

c. IV

d. V

e. VI

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In meiosis two, cytokinesis results in the production of: 

a. Two haploid daughter cells

b. Four diploid daughter cells

c. Four haploid daughter cells

d. Two diploid daughter cells

 

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In meiosis, the separated sister chromatids move to opposite poles of the cell during: 

a. Metaphase one

b. Metaphase two

c. Anaphase one

d. Telophase one

e. Anaphase two

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In meiosis, chromosomes containing sister chromatids (not homologous chromosomes) align along the center of the cell during: 

a. Prophase one

b. Prophase two

c. Interphase two

d. Metaphase one

e. Metaphase two

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In meiosis, paired homologs align down the center of the cell during: 

a. Metaphase one

b. Prophase one

c. Prophase two

d. Metaphase two

e. Anaphase two

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In meiosis 1, cytokinesis usually occurs after telophase one and produces: 

a. One diploid cell

b. Two haploid cells

c. Four haploid cells

d. Two diploid cells

e. One haploid cell

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Meiotic cell division replicates a cell's DNA ____________ and then divides ______________. 

a. Twice, once

b. Once, twice

c. Twice, twice

d. Once, once

e. None are correct

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Each gamete arises from a diploid cell containing two sets of homologous chromosomes. 

a. True   

b. False

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Gametes may carry different combinations of alleles because of: 

a. Random fertilization

b. Random fertilization and crossing over

c. Random alignment of chromosomes

d. Crossing over and random alignment of chromosomes

e. Random fertilization and alignment of chromosomes

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All gametes contain:  

a. Two identical sets of chromosomes

b. Two different sets of chromosomes

c. One set of chromosomes

d. One chromosome

e. Two chromosomes

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Gametes:

a. 2n

b. n

c. 2n

d. ½ n

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The end of Anaphase II results in cells of what ploidy?

a. 2n

b. n

c. 2n

d. ½ n

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Prophase II:

a. 2n

b. n

c. 2n

d. ½ n

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Anaphase I:

a. 2n

b. n

c. 2n

d. ½ n

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Telophase II:

a. 2n

b. n

c. 2n

d. ½ n

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The cells created in Meiosis I have what ploidy?

a. 2n

b. n

c. 2n

d. ½ n

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Meiosis II:

a. 2n

b. n

c. 2n

d. ½ n

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If a horse (2n= 32) cell proceeds through meiosis 1 and 2 and then:

How many chromatids will be in the tetrads formed in Prophase I?

a. 32

b. 16

c. 64

d. 128

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