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Biology

Cells, DNA, ecosystems and the machinery of living things.

Core concepts

DNA

A four-letter code (A, T, G, C) spiralled into a double helix. Three letters spell one amino acid.

Photosynthesis

Plants turn light, water and CO₂ into sugar and oxygen — the energy source for almost all life.

Natural selection

Traits that help survival get passed on more often. Over generations, populations shift.

Key formulas

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