In AQA triple science Physics, Chemistry and Biology the different papers examine different topics, as EllenJane said.
Physics Paper 2:
Forces & moments
Velocity & acceleration
Momentum
Pressure
Waves, sound
Electromagnetic spectrum
Light
Electromagnetism
Space
Chemistry paper 2:
Rates & equilibrium
Hydrocarbons & fuels
Organic reactions
Polymers
Tests for ions & gases
The atmosphere
Water resources
Metal extraction
Haber process
Fertilisers
Biology paper 2:
Nervous system, brain, eye
Homeostasis
Hormones
Menstrual cycle
Fertility
Plant hormones
The kidney
Reproduction
DNA
Genetics
Variation
Genetic engineering
Cloning
Evolution
Extinction
The above lists are for AQA triple sciences (higher)