Which of the individuals below is represented by the following karyogram?
A male with a chromosomal abnormality
A genetically normal female
A male with Down syndrome (Trisomy 21)
A female with Down syndrome (Trisomy 21)
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Which of the following processes involve mitosis?
growth, repair, semi-conservative replication
repair, growth, asexual reproduction
reduction division, asexual reproduction, growth
repair, reduction division, asexual reproduction
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The micrograph below show cells that are in various stages of the cell cycle.
Doc. RNDr. Josef Reischig, CSc., CC BY-SA 3.0, via Wikimedia Commons (opens in a new tab)
Which of the following correctly identifies the stages of mitosis for cells P, Q and R?
| P | Q | R |
A | Prophase | Metaphase | Anaphase |
B | Metaphase | Telophase | Anaphase |
C | Telophase | Metaphase | Anaphase |
D | Prophase | Anaphase | Metaphase |
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Which of the following statements apply to the process of crossing over in meiosis?
I. Crossing over occurs between non-homologous sister chromatids
II. Crossing over occurs between non-sister homologous chromatids
III. Crossing over results in genetic recombination
IV. Unequal-length sections of DNA routinely cross from one strand to another during crossing-over
I, III, and IV only
II and III only
II and IV only
II, III, and IV only
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Which row of A - D shows the correct names of the phases of meiosis I pictured below?
| 1 | 2 | 3 | 4 | 5 |
A | anaphase | telophase | prophase | metaphase | interphase |
B | metaphase | interphase | telophase | prophase | anaphase |
C | metaphase | telophase | interphase | prophase | anaphase |
D | anaphase | interphase | prophase | telophase | metaphase |
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Which stage of meiosis I is displayed in the image?
Metaphase
Prophase
Anaphase
Telophase
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Which of the following materials and pieces of laboratory equipment can be used to develop and refine our understanding of meiosis?
I. light microscopes
II. staining compounds
III. animal body cells
IV. plant sex organs
I. and III.
I. II. and IV.
I. and IV.
II. III. and IV.
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Five events that take place during meiosis are listed.
Which is the correct chronological order (1 - 5) of those events?
1 | crossing over |
2 | haploid gametes form |
3 | formation of bivalents |
4 | reduction division |
5 | replication of DNA |
1 | haploid gametes form |
2 | reduction division |
3 | formation of bivalents |
4 | crossing over |
5 | replication of DNA |
1 | replication of DNA |
2 | formation of bivalents |
3 | crossing over |
4 | haploid gametes |
5 | form reduction division |
1 | replication of DNA |
2 | formation of bivalents |
3 | crossing over |
4 | reduction division |
5 | haploid gametes form |
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If an organism has 11 pairs of chromosomes, which mathematical equation will calculate the number of combinations in which homologous chromosomes can orientate themselves during meiosis I?
The calculations shown in the choices are all mathematically correct.
211 = 2 048 combinations
222 = 484 combinations
222 = 4 194 304 combinations
112 = 121 combinations
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Which is the best explanation for the term reduction division as it relates to meiosis?
The mass of DNA in each cell has been reduced.
The overall amount of DNA has been reduced during meiosis.
The chromosome number has been reduced.
DNA is chemically reduced during the process of meiosis.
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Exchange of alleles is an important feature of meiosis.
During which precise stage of meiosis does the exchange of alleles take place?
When crossing over occurs between two non-sister chromatids
When homologous chromosomes are oriented at the cell equator
When new nuclei form
During gene linkage
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The image shows a human karyotype of cells taken from amniocentesis in the later stages of the first half of a pregnancy.
What conclusion can be drawn from this karyotype?
The foetus's karyotype is entirely normal.
The foetus has Down syndrome.
The foetus has trisomy 18 (Edward's syndrome) and is unlikely to survive beyond the age of 12 months.
The foetus is female.
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Which statement best describes the cells produced as a result of meiosis?
Haploid and genetically identical.
Diploid and genetically identical.
Haploid and genetically different.
Diploid and genetically different.
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The photomicrograph shows cells in different stages of mitosis.
In which order do these stages occur?
4 → 1 → 3 → 2 → 5
4 → 1 → 2 → 3 → 5
4 → 3 → 5 → 1 → 2
4 → 5 → 1 → 2 → 3
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Which of the following do(es) not happen during an animal cell cycle?
I. DNA is transcribed and translated
II. The spindle is formed from microtubules
III. A cell plate forms to divide daughter cells
IV. Plasma membrane is pulled inwards around the cell equator to form a cleavage furrow
III only
I and III only
II only
IV only
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Each of the following events takes place during mitosis:
1 | Chromosomes decondense |
2 | Chromatids move to opposite poles of the cell |
3 | Centromeres divide |
4 | Chromosomes line up along the equator |
5 | The nuclear membrane breaks down |
In which order do the events take place?
| First → → → Last | ||||
A | 1 | 2 | 4 | 5 | 3 |
B | 3 | 1 | 2 | 4 | 5 |
C | 4 | 5 | 3 | 1 | 2 |
D | 5 | 4 | 3 | 2 | 1 |
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The diagram shows the chromosomes of a squashed cell during mitosis.
What is the stage of mitosis and the haploid chromosome number for this cell?
| Stage of mitosis | Haploid chromosome number |
A | Early prophase | 10 |
B | Late prophase | 5 |
C | Metaphase | 10 |
D | Anaphase | 5 |
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The diagram below shows a plant life cycle. It includes unfamiliar stages such as ‘sporophyte’ and ‘gametophyte’ that are not found in human life cycles.
What process is taking place at the stage marked X on the diagram?
Fertilisation
Meiosis
Fusion
Mitosis
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Which of the individuals described below does the following karyogram represent?
A male with Down syndrome.
A male with a chromosome abnormality.
A healthy male.
A female with Down syndrome.
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Which of the following gives an accurate definition of genetic recombination?
The orientation of homologous chromosomes as they align during metaphase I of meiosis
The development of new alleles within a population through mutation
The breaking and rejoining of DNA to create new combinations
The loss of DNA telomeres through multiple cycles of replication
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Which of the following most accurately describes the events that occur in meiosis I?
A | Chromatids separate | Crossing over occurs in prophase I |
B | Chromatids separate | Crossing over occurs in metaphase I |
C | Homologous chromosomes separate | Crossing over occurs in prophase I |
D | Homologous chromosomes separate | Crossing over occurs in metaphase I |
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The diagram shows a pair of homologous chromosomes at the beginning of prophase I of meiosis, and four possible examples of crossing over, A - D
Which of the four representations of crossing over cannot occur in meiosis I?
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For a eukaryotic organism with a diploid number of 14, which option gives the number of chromosome combinations that can occur as a result of random orientation in meiosis?
Note that all the equations below are mathematically correct.
14
128
16 384
2 097 152
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Which of the following statements correctly describes meiosis?
It is a mechanism of nuclear division that occurs in all cells.
It produces haploid cells during the first nuclear division.
It involves interphase, prophase, metaphase, anaphase and telophase.
It is the only process that generates genetic variation.
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The diagram below shows the life cycle of a fern. The term 2n is used to represent diploid cells and the term n is used to represent haploid cells.
Which stage represents meiosis?
W
X
Y
Z
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Which events are taking place at stages 1, 2, and 3 in the diagram of meiosis below?
| 1 | 2 | 3 |
A | DNA replication | Random fertilisation | Sister chromatids become chromosomes |
B | Mitosis | Separation of homologous pairs | Separation of sister chromatids |
C | DNA replication | Random orientation | Separation of homologous pairs |
D | DNA replication | Crossing over | Separation of sister chromatids |
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Which of the following statements about genetic variation and meiosis are correct?
I. Meiosis generates genetic variation through crossing over, random orientation, and random fusion of gametes.
II. The number of different combinations of chromosomes that are possible as a result of random orientation is 2n, where n is the number of chromosomes in a diploid cell.
III. Crossing over can take place at any location along a chromosome
I only
I and III only
II and III only
I, II, and III
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A group of scientists carried out a study looking at the relationship between the number of crossing over events taking place during meiosis and the distance between the crossing over events and the centromere in male trout (a species of fish). Some of their results are shown in the graph below.
What can be concluded from the graph?
There are significantly more crossing over events further away from the centromere.
30 % of crossing over events occur at a relative distance of 0.6.
A higher percentage of crossing over events take place as distance from the centromere increases in male trout.
A higher percentage of crossing over events take place as distance from the centromere increases in fish species.
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Some scientists were investigating mitosis in plant cells. They applied a chemical agent called colchicine which interferes with tubulin proteins in the cytoplasm. An image of some chromosomes from a treated cell can be seen below.
How does treatment with colchicine prevent the progression of cell division in plant cells?
Cells cannot progress past interphase as the chromosomes are decondensed
Cells cannot progress into prophase as spindle fibres have not formed
Cells cannot progress into anaphase as spindle fibres have not formed
Cells cannot progress past metaphase as chromosomes are decondensed
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Which of the following is the best explanation of why the lengths of DNA exchanged during crossing-over tend to be the same length as each other?
Breakages occur where distinct alleles fail to line up accurately with each other in the formation of a tetrad
If uneven lengths of DNA are crossed over, restriction enzymes will trim off the unnecessary DNA from the longer chromatid
There is a lack of space in the tightly-packed ball of condensed chromosomes in prophase I, so only short lengths of DNA can cross over
Breaks occur in the same base sequences on each non-sister chromatid
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The micrographs below show cells undergoing meiosis.
Which sequence correctly identifies the stage of meiosis in each micrograph from left to right?
Metaphase I, anaphase I, prophase I, telophase I
Metaphase II, anaphase II, prophase II, telophase II
Prophase II, anaphase II, metaphase II, telophase II
Prophase I, anaphase I, metaphase I, telophase I
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The micrograph below shows an image of a cell undergoing meiosis.
Which stage of meiosis can be seen in the image, and why?
| Stage of meiosis | Reason |
A | Prophase II | Chromosomes are condensed and randomly arranged in the cell |
B | Prophase I | Chromosomes are condensed and randomly arranged in the cell |
C | Prophase I | Chromosomes are condensed in a haploid cell |
D | Metaphase I | Chromosomes are lined up down the centre of a cell |
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The following choices each show a bivalent.
Along the length of the bivalent are some values of probability.
Which choice reflects the most likely probabilities of a chiasma forming at each of the positions shown?
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Which row best describes an organism whose diploid number is 16 and whose body cells have an amount of DNA, x?
| Number of chromosomes per body cell | Number of centromeres | Amount of DNA per cell at the beginning of meiosis I |
A | 16 | 16 | 2x |
B | 8 | 16 | 2x |
C | 16 | 8 | 4x |
D | 8 | 8 | x |
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The fungus Sordaria fimicola is an excellent organism for observing the effects of meiosis because its gametes (spores) are coloured and can be observed under a microscope.
Wild-type fungus has black spores. Another variety has tan spores.
The allele for black spores is B and the allele for tan spores is b.
These can be crossed to produce a diploid zygote, which can then undergo meiosis to produce spores. In this species, a final mitotic division results in 8 spores produced as shown below.
Each zygote produces its eight spores in a structure called an ascus, in which the eight spores line up to reveal the alignment of homologous chromosomes during the meiotic division that led to their formation.
A microscope image of some asci is shown below.
Which asci, labelled 1 - 4 in the microscope view above, show evidence that crossing over has taken place?
All of them
2 and 3
1 and 3
2 and 4
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