Cells & Division is a core part of IB Biology. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
PhospholipidAmphipathic lipid forming the bilayer
Fluid mosaicSinger-Nicolson 1972 model of membranes
Integral proteinSpans the bilayer (e.g. channel, carrier)
Peripheral proteinAttached to one surface only
Facilitated diffusionPassive transport via protein channel
Active transportEnergy-using transport against gradient
InterphaseG1 + S + G2; cell grows and replicates DNA
MitosisNuclear division yielding two identical nuclei
CyclinRegulatory protein activating CDKs at checkpoints
CentromereRegion where sister chromatids attach
SpindleMicrotubule apparatus that pulls chromosomes
TumourMass from uncontrolled mitosis (mutation)
ProkaryoteCell without membrane-bound nucleus (bacteria, archaea)
EukaryoteCell with true nucleus and organelles
Common mistakes to avoid
Questions where students often pick the tempting wrong answer — make sure you know the right one:
Do animal cells have a cell wall?✗ Yes, all cells have a cell wall. ✓ No — only plant cells (and bacteria/fungi) have a cell wall.
Does diffusion require energy from the cell?✗ Yes, diffusion uses energy like active transport. ✓ No — diffusion is passive and needs no energy.
Which cells contain mitochondria?✗ Only muscle cells have mitochondria. ✓ Most cells do; very active cells like muscle have many.
Are all cells in an organism identical?✗ Yes, every cell is exactly the same. ✓ No — cells are specialised (differentiated) for their functions.
Where is DNA found in a cell?✗ Only in the nucleus. ✓ Mainly in the nucleus, but also in mitochondria (and chloroplasts).
Practise Cells & Division — free games
Test yourself with these quick revision games for this topic:
See all 17 games in the Subjects Arcade →
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