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Kristin Fracchia

Science Topics on the ACT

The ACT Science section will occasionally include questions in which the answer requires science knowledge that is not provided in the passage.

Here is a list of basic scientific topics that the ACT might test. But don’t panic! Anything tested will be on a very basic level (something you might have learned in an introductory class or even remember from middle school), and you will only see a few questions per test that require any outside knowledge at all.

To get some more tips on ACT science practice, follow this link for strategies, questions and explanations!


  • classifications: genus, species (e.g. knowing that lizards are mammals, reptiles or amphibians)
  • human anatomical systems (circulatory, digestive, respiratory)
  • eukaryotic and prokaryotic organisms
  • photosynthesis
  • pollination
  • metamorphosis
  • genetics (allele, genes, chromosomes, X and Y chromosomes)
  • proteins
  • DNA
  • RNA
  • ribosomes
  • mitochondria
  • chromosome
  • genotype
  • osmosis
  • phenotype
  • ominant and recessive traits
  • crossing over of dominant and recessive alleles
  • mitosis
  • meiosis
  • cellular division phases (interphase, etc.)



  • understanding (and balancing) chemical equations and reactions
  • atom
  • nucleus
  • ion
  • molecule
  • solute
  • solution
  • solvent
  • reactant
  • product
  • solubility
  • atomic mass
  • solid, liquid, gas
  • pH
  • acid
  • base
  • viscosity
  • condensation
  • evaporation
  • electrons
  • protons
  • neutrons
  • atomic number
  • atomic mass
  • molar mass
  • isotopes
  • solid, liquid, gas and melting, boiling, freezing points (very generally speaking; not specific to any particular substance, except maybe water)
  • important elements (e.g. water is H20)



  • velocity
  • acceleration
  • polarity
  • buoyancy
  • waves
  • amplitude
  • frequency
  • wavelength
  • charges (like charges attract; opposite charges repel)
  • circuits (capacitor, resistor)
  • amperes
  • volts
  • convection
  • conduction
  • radiation
  • kinetic energy
  • potential energy
  • gravitational potential energy
  • mechanical energy
  • density


Earth and Space

  • metamorphism (state change)
  • layers of earth
  • erosion
  • altitude
  • air resistance
  • orbit
  • terrestrial planet/gas giants


Other Science Terms

  • independent variable
  • dependent variable
  • control
  • hypothesis
  • endothermic
  • exothermic
  • ectothermic
  • matter
  • mass



All images from Wikimedia Commons: LadyofHats, Emichan & Miraceti, Sharon Bewick, Mats Halldin, Brazosport College


About Kristin Fracchia

Kristin makes sure Magoosh's blogs are chock-full of awesome, free resources for students preparing for standardized tests. With a PhD from UC Irvine and degrees in Education and English, she’s been working in education since 2004 and has helped students prepare for standardized tests, as well as college and graduate school admissions, since 2007. She enjoys the agonizing bliss of marathon running, backpacking, hot yoga, and esoteric knowledge.

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