D2.1 Cell and nuclear division
Practice exam-style IB Biology questions for Cell and nuclear division, aligned with the syllabus and grouped by topic.
Question 1
A parent cell in a living organism divides to form daughter cells. What conclusion follows from this process?
A.
New cells arise by division of pre-existing cells.
B.
Cell division only occurs during sexual reproduction.
C.
The parent cell remains unchanged after producing two daughter cells.
D.
New cells are assembled from non-living chemicals without a parent cell.
Question 2
In animal cell cytokinesis, what produces the cleavage furrow?
A.
Condensation of chromatin around histones
B.
Shortening of kinetochore microtubules
C.
Fusion of vesicles containing cell wall material
D.
Contraction of an actin and myosin ring
Question 3
Budding in yeast is an example of unequal cytokinesis. What feature makes it unequal?
A.
The daughter bud receives a smaller share of cytoplasm than the parent cell.
B.
The parent cell divides its chromosomes unequally in mitosis.
C.
The daughter bud receives no nucleus from the parent cell.
D.
The parent cell produces four haploid nuclei in the bud.
Question 4
What distinguishes mitosis from meiosis in eukaryotes?
A.
Mitosis produces haploid nuclei, whereas meiosis produces diploid nuclei.
B.
Mitosis maintains chromosome number, whereas meiosis halves chromosome number.
C.
Mitosis occurs only in gametes, whereas meiosis occurs only in body cells.
D.
Mitosis does not require DNA replication, whereas meiosis requires DNA replication.
Question 5
A cell has chromosomes aligned across the equator and sister chromatids attached to opposite spindle poles. What phase of mitosis is shown?
A.
Prophase
B.
Metaphase
C.
Anaphase
D.
Telophase
Question 6
What is cell proliferation?
A.
An increase in cell number when division exceeds cell loss
B.
Movement of cells from a primary tumour to another organ
C.
Differentiation of cells into specialized tissues
D.
An increase in cell size caused by uptake of water
Question 7
During which phase of the cell cycle is nuclear DNA replicated?
A.
G2 phase
B.
Cytokinesis
C.
S phase
D.
G1 phase
Question 8
Define cytokinesis.
[1]
Outline cytokinesis in animal cells.
[1]
Question 9
Outline the relationship between DNA replication, chromatids and anaphase. [3]
Question 10
After DNA replication but before anaphase of mitosis, one chromosome consists of what?
A.
Four chromatids arranged as a bivalent
B.
Two sister chromatids held together by cohesin
C.
One chromatid containing one DNA molecule
D.
Two homologous chromosomes joined at a chiasma
Question 11
What is the role of kinetochore microtubules during nuclear division?
A.
They build the plant cell wall between daughter cells.
B.
They hold sister chromatids together until anaphase.
C.
They attach to chromosomes and help move them towards poles.
D.
They synthesize DNA before chromosomes condense.
Question 12
A cell nucleus has a DNA content between the G1 value and the G2 value. What stage is most likely?
A.
S phase
B.
Telophase after cytokinesis
C.
Metaphase
D.
G0 phase
Question 13
Why must mitochondria increase in number during interphase before division?
A.
Mitochondria are destroyed during every prophase.
B.
Mitochondria produce cyclins directly from DNA in the nucleus.
C.
Mitochondria contain the chromosomes that align in metaphase.
D.
Mitochondria can only arise by growth and division of pre-existing mitochondria.
Question 14
What allows a cell to pass a cell-cycle checkpoint according to the cyclin model in this topic?
A.
A specific cyclin reaches a threshold concentration.
B.
All cyclins remain at constant concentration throughout the cycle.
C.
Chromosomes decondense completely during metaphase.
D.
Cytokinesis begins before DNA replication starts.
Question 15
A tumour remains localized and does not invade neighbouring tissue. What term describes it?
A.
Benign
B.
Metastatic
C.
Malignant
D.
Secondary
Question 16
A micrograph shows 18 cells in mitosis out of 150 observed cells. What is the mitotic index?
A.
0.18
B.
8.3
C.
0.12
D.
132
Question 17
Compare cytokinesis in plant cells and animal cells. [4]
Question 18
Human oogenesis involves unequal cytokinesis.
State what is meant by unequal cytokinesis.
[1]
Explain one advantage of unequal cytokinesis in oogenesis.
[1]
Question 19
Explain why nuclear division is needed before cytokinesis in a eukaryotic cell. [3]
Question 20
A drawing shows four cells from a root tip.
Identify the phase in a cell with chromosomes aligned along the equator.
[1]
Identify the phase in a cell with two groups of V-shaped chromatids moving apart.
[1]
Identify the phase in a cell with chromosomes condensing but not aligned.
[1]
Identify the phase in a cell with two reforming nuclei at opposite poles.
[1]
Question 21
Outline how cell proliferation contributes to growth in a root apical meristem. [3]
Question 22
State the sequence of stages in the eukaryotic cell cycle from G1 to completion of cell division, and give one event in S phase. [4]
Question 23
Explain why interphase should not be described as a resting phase. [3]
Question 24
Distinguish between benign and malignant tumours. [4]
Question 25
The visual shows counts of onion root-tip cells classified by stage.
Identify the mitotic phase with the largest number of cells.
[1]
Calculate the percentage of observed cells that are in mitosis.
[1]
Suggest why most cells are not observed in mitosis.
[1]
Question 26
The table compares cytoplasmic volume and organelle content of cells formed during a reproductive process.
| Cell | Cytoplasm / µm³ | Reserve granules | Mitochondria |
|---|---|---|---|
| Cell A | 520000 | Many | Present |
| Cell B | 4000 | None detected | None detected |
Identify whether cytokinesis is equal or unequal.
[1]
Give one reason for your answer.
[1]
Suggest why the smallest cell would be unlikely to develop if it received no mitochondria.
[1]
Question 27
A species has a haploid chromosome number of 6. How many chromosome combinations can be produced by random orientation of bivalents, excluding crossing over?
A.
36
B.
64
C.
6
D.
12
Question 28
What is an oncogene?
A.
A mutated or overactive proto-oncogene that stimulates excessive division
B.
A chromosome copy missing from a haploid gamete
C.
A gene that prevents all cells from entering G0
D.
A normal gene that repairs every mutation before mitosis
Question 29
Explain how chromosomes are condensed and moved during mitosis or meiosis. [4]
Question 30
Explain how meiosis generates genetic variation. [4]
Question 31
Explain how cyclins control progression through the cell cycle. [3]
Question 32
Distinguish between proto-oncogenes and tumour suppressor genes in cell-cycle control. [4]
Question 33
A student counts 240 cells in a stained tumour sample. Of these, 36 cells are in mitosis.
Calculate the mitotic index.
[1]
State what a higher mitotic index suggests about a tumour.
[1]
State one limitation of using mitotic index alone to classify tumours.
[1]
Question 34
The graph shows the incidence of trisomy 21 in live births for different maternal age groups.
Describe the trend shown.
[1]
State the meiotic error that can produce a gamete with an extra chromosome 21.
[1]
Explain how this error can lead to Down syndrome after fertilization.
[1]
Question 35
The diagram shows three bivalents at metaphase I in two different cells of the same species.
State the haploid chromosome number for this species.
[1]
Deduce the number of chromosome combinations possible from random orientation alone.
[1]
Explain how the two cells shown could produce genetically different gametes.
[1]
Question 36
The graph shows DNA content per nucleus measured in a population of dividing cells.
Identify the cell-cycle stage corresponding to the lowest DNA-content peak.
[1]
Identify the stage or stages corresponding to the highest DNA-content peak.
[1]
Deduce which nuclei are in S phase.
[1]
Explain why DNA content changes during the cell cycle.
[1]
Question 37
A pathologist counted cells in micrographs from three tumours and recorded mitotic index and evidence of invasion.
| Tumour | Total cells / cells | Mitotic cells / cells | Mitotic index / % | Invasion |
|---|---|---|---|---|
| A | 400 | 8 | 2.0 | Absent |
| B | 500 | 55 | — | Absent |
| C | 450 | 27 | 6.0 | Present |
Calculate the mitotic index for tumour B from the table.
[1]
Identify the tumour with the highest rate of cell division.
[1]
Explain why evidence of invasion is important in classifying a tumour.
[1]
Evaluate whether mitotic index alone is sufficient to identify a malignant tumour.
[1]
Question 38
A cell has one mutation that increases expression of a proto-oncogene and a second mutation that inactivates a tumour suppressor gene.
Suggest how the first mutation affects the cell cycle.
[1]
Suggest how the second mutation affects the cell cycle.
[1]
Question 39
A student classified cells from a root-tip micrograph into mitotic stages using chromosome appearance.
Identify the phase represented by cells with two chromosome groups at opposite poles and reforming nuclei.
[1]
Describe one feature of anaphase that distinguishes it from metaphase.
[1]
Evaluate one source of uncertainty in classifying real micrographs into mitotic phases.
[1]
Suggest one improvement to increase reliability of the classification.
[1]
Question 40
The graph shows changes in concentrations of three cyclins during one cell cycle. Checkpoint positions are marked.
State the general pattern of cyclin concentration shown.
[1]
Identify the cyclin most likely to permit passage through the checkpoint before mitosis.
[1]
Explain how cyclins control progression through checkpoints.
[1]
Suggest one consequence if a cyclin remained high when it should decrease.
[1]
Question 41
The graph shows cell numbers in a skin wound margin over several days after injury.
Describe the change in cell number over time.
[1]
Suggest the process responsible for the increase in cell number.
[1]
Explain why surviving cells near the wound are important for repair.
[1]
Question 42
Outline the events of metaphase and anaphase in mitosis.
[1]
Explain how mitosis produces two genetically identical daughter nuclei.
[1]
Question 43
Outline one role of mitosis and one role of meiosis in eukaryotes.
[1]
Compare and contrast mitosis and meiosis in terms of chromosome number, genetic variation and chromosome segregation.
[1]
Question 44
Outline the sequence of stages in the cell cycle used for cell proliferation.
[1]
Explain the importance of events during interphase for successful cell division.
[1]
Question 45
The table shows mutation status for cell-cycle control genes in four cell samples and whether uncontrolled division was observed.
| Sample | Proto-oncogene activated | Tumour suppressor copies lost | Mutagen exposure | Division rate category |
|---|---|---|---|---|
| A | No | 0 | No | Normal |
| B | Yes | 0 | No | Raised |
| C | No | 1 | Yes | Slightly raised |
| D | Yes | 2 | Yes | Uncontrolled |
Identify the sample with the greatest risk of uncontrolled division based on the table.
[1]
Explain how an activating mutation in a proto-oncogene can affect division.
[1]
Explain how loss of tumour suppressor gene function can affect division.
[1]
Evaluate why several mutations in the same cell lineage may be more dangerous than a single mutation.
[1]
Question 46
Define bivalent and chiasma.
[1]
Explain how meiosis and fertilization contribute to variation in sexually reproducing organisms.
[1]
Question 47
Outline non-disjunction in meiosis.
[1]
Explain how non-disjunction can cause Down syndrome and why meiosis is necessary in a sexual life cycle.
[1]
Question 48
Outline the roles of proto-oncogenes and tumour suppressor genes in normal cell-cycle control.
[1]
Discuss how mutations in these genes can lead to tumour formation.
[1]
Question 49
Define mitotic index and metastasis.
[1]
Evaluate the use of mitotic index and tissue invasion to distinguish between tumour types.
[1]
Question 50
Outline two contexts in which cell proliferation occurs in multicellular organisms.
[1]
Discuss how regulated and deregulated cell proliferation affect growth, replacement, repair and cancer risk.
[1]
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