Mitosis and the cell cycle
1.
Read through the following account of mitosis in an animal cell, then write on the dotted
lines the most appropriate word or words to complete the account.
During prophase, the ................................................ breaks down and the
................................................ migrate to opposite poles of the cell.
During ................................................, the chromosomes are visible as pairs of
chromatids, lined up along the equator of the cell. Spindle fibres extend from the poles
of the cell and attach to the ................................................ .
In ................................................, the spindle fibres contract, pulling the chromatids
apart.
(Total 5 marks)
2.
In a study of plant structure, a leaf cell and a cell from a root tip were observed.
(a)
Name one structure that may be found in a leaf cell that identifies it as both a
eukaryotic cell and a plant cell.
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(1)
(b)
The cell from the root tip was observed to be undergoing anaphase of mitosis.
(i)
Describe anaphase of mitosis.
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(3)
(ii)
During anaphase, the cell from the root tip did not have a nucleus but was
still considered to be eukaryotic. Suggest two reasons why this cell was still
considered to be eukaryotic.
1 .......................................................................................................................
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2 .....................................................................................................................
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(2)
(c)
The table below shows the number of cells at each stage of the cell cycle in one
sample of tissue taken from the growing region of a plant root.
Stage of the cell
cycle
Number of cells in
each stage
Percentage of cells in
each stage (%)
Interphase
47
78.3
Prophase
3
5.0
Metaphase
3.3
Anaphase
1
1.7
Telophase
3
5.0
Cytokinesis
TOTAL
(i)
6.7
60
100
Complete the table by calculating the number of cells undergoing metaphase
and cytokinesis. Give your answer to the nearest whole number.
(2)
(ii)
Using the table above, suggest which stage of the cell cycle takes the
longest. Give a reason for your answer.
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(2)
(iii)
Suggest one reason why your answer to (c)(ii) may be unreliable.
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(1)
(Total 11 marks)
3.
The diagrams below show some cells in different stages of mitosis.
A
B
C
D
(a)
Name the stages of mitosis shown by the cells labelled A, B and C.
A .................................................................................................................................
B .................................................................................................................................
C .................................................................................................................................
(3)
(b)
Describe the events that occur in the stage of mitosis shown by cell D.
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(2)
(c)
Explain the significance of the stage shown by cell D.
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(1)
(Total 6 marks)
4.
The drawing below shows an animal cell, magnified × 1000, undergoing mitosis.
(a)
Give two features that help to identify this as an animal cell.
1 .................................................................................................................................
2 .................................................................................................................................
(2)
(b)
Name the parts labelled A and B.
A ................................................................................................................................
B ................................................................................................................................
(2)
(c)
Name the stage of mitosis shown in the drawing.
....................................................................................................................................
(1)
(Total 5 marks)
5.
(a)
The table below describes some of the key events that occur during mitosis
Complete the table by writing the name of the stage of mitosis next to its
description.
Key events
Stage
Chromatids separate and move to opposite poles
of the dividing cell.
Chromosomes shorten and thicken. The nuclear
envelope breaks down and the spindle forms.
The spindle fibres break down, the nuclear
membrane re-forms and the chromosomes
elongate.
Chromosomes line up on the equator of the cell,
attached to spindle fibres by their centromeres.
(4)
(b)
The graph below illustrates the change in DNA content during the cell cycle
Mass of DNA /
arbitrary units
6
C
5
D
4
3 A
B
2
G1
1
0
0
2
4
6
8
10
12
14
16
18
20
22
24
Time / hours
26
(i)
Calculate the percentage of the cell cycle time spent in G1.
Answer...................................................................
(3)
(ii)
At which point, A, B, C or D, does chromosome replication (the S phase)
begin? Explain your answer.
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(2)
(Total 9 marks)
6.
The diagram below shows the structure of a chromosome as it might appear at the end of
prophase of mitosis.
A
(a)
B
Name the parts labelled A and B.
A .................................................................................................................................
B .................................................................................................................................
(2)
(b)
During metaphase of mitosis, the chromosomes become attached to the equator of
the spindle. Name the stage of mitosis that follows metaphase and describe the
events that occur in this stage.
Stage ...........................................................................................................................
Events occurring ........................................................................................................
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(3)
(c)
Explain the significance of the stage you have named and described in (b).
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(1)
(d)
Mitosis forms part of the cell cycle. Name one other stage of the cell cycle and
state what occurs in the stage that you have named.
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(2)
(Total 8 marks)
Mark Scheme
1.
Nuclear {membrane / envelope} / nucleolus;
Centrioles;
Metaphase;
Centromeres / kinetochore / chromosome;
Anaphase;
[5]
2.
(a)
(b)
chloroplast / (sap / large / permanent) {vacuole / vacuole membrane
/ tonoplast} / cellulose cell wall;
(i)
(ii)
(c)
1.
spindle fibres contract / eq;
2.
{chromatids / daughter chromosomes / eq};
3.
{pull apart / separate / eq};
4.
reference to kinetochore / centromere leads;
5.
move to opposite {poles / eq} of cell;
1.
membrane bound organelles {present / eq} / correctly named
organelle e.g. mitochondrion;
2.
has {80s / large} ribosomes;
3.
nucleus will reform / eq;
4.
presence of cellulose cell wall;
3 max
2 max
(i)
Stage of the
cell cycle
Interphase
Prophase
Number of
cells in each
stage
1
Percentage
in each
stage (%)
Metaphase
2;
Anaphase
Telophase
Cytokinesis
4;
TOTAL
2
(ii)
(iii)
1.
interphase;
2.
most found at this stage (at any one time) / correct reference to
|figure from table;
2
not enough {data / samples / cells / slides} {observed / counted} / (data)|
only taken from one point in time;
1
[11]
3.
(a)
(b)
(c)
A
Metaphase;
B
Prophase;
C
Telophase;
1.
Chromatids separate / centromere splits;
2.
Moved to (opposite) {poles / ends / centrioles};
3.
By spindle fibres / microtubules;
4.
Shortening / eq;
Daughter cells genetically identical to parent cell / maintains
chromosome number / eq;
3
2
1
[6]
4.
(a)
centrioles / centrosomes;
asters;
no cell wall;
[ignore chloroplasts and vacuole]
(b)
(c)
A
B
chromatid / chromosome / daughter chromosome;
spindle (fibres) / microtubules;
anaphase; [ignore I or II]
2
2
1
[5]
5.
(a)
anaphase ;
prophase ;
telophase ;
metaphase ;
[if ‘I’ or ‘II’, penalise ONCE]
(b)
(i)
4
(G lasts) 7.0 hrs (and cell cycle time is 14 hrs) / 18-11 ;
7 × 100 ÷ 14 ;
(ii)
= 50 % ;
3
B;
DNA replication / DNA mass beginning to, increase / double ;
2
[9]
6.
(a)
A - chromatid;
B- centromere;
(b)
2
Anaphase;
Chromatids separate / centromere splits
Move / pulled to (opposite) poles / ends of cell / ends of spindle to centrioles ;
(c)
(d)
By spindle fibres / microtubules
3
Daughter cells genetically identical (to parent cell) /maintains
chromosome number/eq;
1
Interphase / G1 / S / G2 / cytokinesis / cleavage
If interphase or named stage - growth/synthesis of organelles
synthesis / replication of DNA / division of organelles
OR
If cytokinesis - division of the cytoplasm / formation of cell plate in plants ;
Points linked. [if give ‘telophase’and then describe division of
cytoplasm allow second mark]
2