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D2.1.13 (HL)—Cell cycle phases

The cell cycle includes interphase, mitosis and cytokinesis, with growth, synthesis and preparation phases readying cells for division and growth.

Syllabus
First assessment 2025
Objective
D2.1.13
Level
HL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceMay 2022
Most common paperPaper1
Typical marks1–7

Common command terms

  • Identify
  • Describe
  • Outline
  • Compare
  • Deduce

Scoring notes

Common mistake
Putting S phase after G2 or after mitosis instead of between G1 and G2.

Recent exam appearances

May 2022Paper1 ["HL"] · TZ14[ 1 ]D2.1.13 (HL)—Cell cycle phases
May 2017Paper2 ["HL"] · TZ28(a)[ 4 ]D2.1.13 (HL)—Cell cycle phases
May 2015Paper2 ["HL"] · TZ28(c)[ 7 ]D2.1.13 (HL)—Cell cycle phases
May 2014Paper1 ["HL"] · TZ15[ 1 ]D2.1.13 (HL)—Cell cycle phases
Practice this objective

Coverage 2014–2022 · Updated 16 Jul 2026

The Cell Cycle Coordinates Growth and Division

HL only

The cell cycle is the ordered sequence G1 → S → G2 → mitosis → cytokinesis that enables cell proliferation.

Stage Main event
G1 Cell grows and synthesizes components
S DNA is replicated
G2 Further growth and preparation for nuclear division
Mitosis The nucleus divides and chromosomes are segregated
Cytokinesis The cytoplasm splits to form daughter cells

G1, S and G2 together form interphase; mitosis follows interphase, and cytokinesis completes production of separate daughter cells.

Interphase is not a stage of mitosis. Checkpoint control belongs to the later cyclin Objective; this card establishes the cycle's sequence.

Cell cycle phases

HL only

Assessment in practice

1–2 marks
How it is assessed

This objective is assessed through structured response, commonly using Identify / Describe / Outline.

Command terms

Identify / Describe / Outline / Compare / Deduce

What earns marks

Build the answer around this relationship: The cell cycle sequence is G1, S, G2, mitosis and cytokinesis.

Watch for

Putting S phase after G2 or after mitosis instead of between G1 and G2.

Representative question

Question 1

[Maximum number: 7]

Following germination of seeds, plants undergo a rapid increase in the number of cells. Describe stages in the cell cycle that result in this increase of cells.

HL Cell Cycle and Cancer

HL only

Cell proliferation increases cell number by repeated mitosis, as in plant meristems, early embryos, skin replacement, and wound healing. The cell cycle includes interphase, mitosis, and cytokinesis; interphase has G1 growth, S-phase DNA replication, and G2 preparation. Interphase is metabolically active, not resting; cells synthesize proteins, replicate DNA, grow cytoplasm, and increase organelles. Cyclin concentrations rise and fall to activate cyclin-dependent kinases; CDK-cyclin complexes such as MPF control checkpoints and mitosis entry. Proto-oncogene activation and tumour suppressor loss disrupt checkpoints; accumulated mutations can cause uncontrolled proliferation and cancer. Benign tumours grow locally, malignant tumours invade neighbouring tissues, and metastasis spreads cancer cells to form secondary tumours.

Concept essentials

  • The cell cycle sequence is G1, S, G2, mitosis and cytokinesis.
  • DNA replication occurs during S phase.
  • G1 and G2 involve growth, metabolism and preparation.
  • Mitosis divides the nucleus, and cytokinesis divides the cytoplasm.