IB Biology HL D2.1 Cell and Nuclear Division Questions
Practise IB Biology HL D2.1 by identifying cell-division stages, explaining meiosis outcomes and interpreting chromosome evidence.
- Syllabus
- First assessment 2025
- Course
- Biology HL
- Level
- HL
Exam points
- explain how mitosis generates new cells and maintains chromosome number in growth or asexual reproduction
- compare animal cleavage furrows with plant cell plates and organelle distribution during cytokinesis
- explain DNA replication in S phase and calculate chromatid number after replication
- identify shared mitosis/meiosis chromosome events, including sister-chromatid separation
- sequence and identify mitotic phases from chromosome, spindle, nuclear and micrograph evidence
- calculate mitotic index from cell counts and interpret changes in meristems or inhibitor data
- sequence G1, S, G2, mitosis and cytokinesis; relate interphase to growth, replication and organelle duplication
- link changing cyclin levels and CDK activation to cell-cycle checkpoints, transitions and spindle progression
- trace meiosis I/II from homologous- to sister-chromatid separation and identify haploid outcomes
- diagnose meiotic non-disjunction from chromosome counts or karyotypes for aneuploidy
- explain gamete variation through crossing over, independent assortment and fertilisation
- link proto-oncogene activation or tumour-suppressor loss to checkpoint failure and tumour growth
- identify metastasis when cancer cells form a secondary tumour in a distant organ
Covered syllabus points
D2.1.1—Generation of new cellsD2.1.2—CytokinesisD2.1.3—Equal and unequal cytokinesisD2.1.4—Roles of mitosis and meiosisD2.1.5—DNA replication prerequisiteD2.1.6—Shared featuresD2.1.7—Phases of mitosisD2.1.8—Identification of mitosis phasesD2.1.9—Meiosis as reduction divisionD2.1.10—Down syndromeD2.1.11—Meiosis generates variationD2.1.12 (HL)—Cell proliferationD2.1.13 (HL)—Cell cycle phasesD2.1.14 (HL)—Cell growth during interphaseD2.1.15 (HL)—Cell cycle control by cyclinsD2.1.16 (HL)—Mutations in cell cycle genesD2.1.17 (HL)—Tumour differences
Question 1
[Maximum number: 1]
What describes nuclear division in stem cells?
A
Clonal selection
B
Mitosis
C
Cytokinesis
D
Meiosis
B
Question 2
[Maximum number: 8]
Eukaryotes are a diverse group of organisms, including animals and plants.
Compare and contrast the processes of mitosis and cytokinesis in animal and plant cells.
Similarities: [6 max]
a. (in both plants and animals) produces two genetically identical daughter cells;
b. maintains the chromosome number/genome of cell / produces diploid/2n cells;
c. used for generation of new cells/cell replacement/tissue repair/growth;
d. in prophase the chromatin/chromosome condenses/formation of chromatids/supercoiling of chromosomes;
e. supercoiling of DNA around histones (to form nucleosomes);
f. microtubules/microtubule motors to move chromosomes/chromatids;
g. in metaphase chromosomes align in equator of cell;
h. in anaphase separation of chromatids;
i. in telophase two nuclei/cells form / nuclear membrane/envelope reforms
OR
cytokinesis is the division into two cells;
Differences:
j. in animal cell centrosomes/centrioles facilitates the organization of the mitotic spindle/ spindle poles/microtubules;
k. in plant cells spindle fibres attach to walls;
l. in animal cells, the plasma membrane is pulled inwards around the equator to form a cleavage furrow in cytokinesis
OR
in animal cells actin and myosin pinch cell membrane to split cytoplasm/cytokinesis;
m. in plant cells a cell plate forms (at the equator) to develop into the new cell wall to achieve cytokinesis
OR
in plant cell vesicles (containing pectin) assemble sections of membrane/cell wall (at/across the equator) to achieve splitting/cytokinesis;
Marking guidance:
Max 6 for similarities.
Allow clearly annotated diagrams.
8 max
Question 3
[Maximum number: 4]
The genome is the total of all the DNA in an organism, containing all the genetic information required for development and growth.
Distinguish between cell division by mitosis and by meiosis in eukaryote cells.
| Mitosis | Meiosis | |
|---|---|---|
| a. | maintains chromosome number/diploid | halves chromosome number/haploid |
| b. | for growth/repair | for gamete production |
| c. | in somatic cells | in reproductive/sex/gamete cells |
| d. | one division | two divisions |
| e. | no exchange of genetic material between chromosomes/crossing over | exchange of genetic material between chromosomes/crossing over |
| f. | results in two cells | results in 4 cells |
| g. | only divides chromatids/chromatids separate during anaphase | also divides homologous chromosomes/homologous chromosomes separate during anaphase 1 and (sister) chromatids separate during anaphase 2 |
| h. | genetically identical | genetically different |
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